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Welcome back.

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In a previous lecture in the Lua basics section, we learned about error messages and handling errors

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using the Pcall function.

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Now that we're diving into the Roblox API, it's time to continue expanding our error handling arsenal

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by taking a look at some of the tools studio offers for debugging errors, and also looking at the documentation

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to spot any functions we should wrap in a PE call.

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Now.

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Earlier we took a look at breakpoints, which are those nifty little things you can add in your scripts,

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which will halt the execution of the script, and it will allow you to go line by line, taking a look

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at how your code is executing.

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But you probably didn't know that there are even more settings that we can access with breakpoints.

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So with this example code I have here, I'm going to add a breakpoint at the calling of the main function.

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And then we can right click our breakpoint to access a new window for editing some settings in the breakpoint.

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In fact, there are some settings where we can have the breakpoint be reached or used.

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When only a certain condition is met, we can have it print a message out into the console, and we

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can even continue the execution of this script without halting the script and going line by line.

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Instead, if we want a breakpoint to act purely as like a log message, then we can hit continue execution,

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and then we can print a log message in here.

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And then the format of this log message has to be the same as if you were, let's say, putting some

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arguments in a print statement.

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So for example it says quotation the value of n colon quotation.

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And then you do comma n.

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If you want to print out a variable in your log message.

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We also have an option if we want to delete the breakpoint once we hit it.

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So if you only want to reach a breakpoint once when you're debugging, you can enable that setting and

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then it will automatically remove the breakpoint for you.

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And then we also have some different contexts in here.

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So for example, if your breakpoint is in a module script that could get required by the client or the

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server, and you only want to debug an error that's occurring on the server, well, you can get rid

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of the context on the client.

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And then this other context down here called edit.

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I believe this is only for plugins, so you don't need to worry about that.

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But the two you want to focus on are going to be the client and the server.

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But as you can see, there's just a whole bunch of different options here with breakpoints.

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So let's go ahead and actually take an example of utilizing some of these settings.

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So what I'm going to do is I'm actually going to create a variable before our breakpoint.

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Let's just call it uh example var and we're going to set it equal to ten.

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Now let's say we only want to reach this breakpoint when example var is equal to 20.

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So what we can do is we can type out the variable name which is going to be example var.

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And since this has to be an expression we're going to do equal equal 20.

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So if this evaluates to true we're going to reach our breakpoint.

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And then when we also reach our breakpoint let's go ahead and print a message like the value of example

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var is.

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We need to close that with quotations since this is a string.

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And then we're going to put a comma and then do example var.

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So this is the exact same way as if you were typing in arguments for a print statement.

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And then we're going to continue execution and not halt the code.

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So let's go ahead and save that.

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You're going to see that the symbol has changed for our breakpoint, because now it is a log point because

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we're printing out a log message.

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But let's go ahead and run this code.

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And what you're going to see is nothing happened.

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We got the print statements that were inside of our function.

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For example, it prints before division and then it prints the result after the division.

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But you see, it didn't print the message from our log point.

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And that's because this condition evaluated to false.

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Now if we went and set example of are equal to 20 and then we run it.

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As you can see the value of example var is 20.

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So our break point was reached.

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It printed in the console.

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And that's because the condition inside of our break point evaluated to true.

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And then it also didn't halt the execution of our script because we have continue execution enabled

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If we decide to disable that.

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And then actually let me make sure it's disabled, okay, it's disabled.

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And then if we were to run the code again, as you can see, we get put inside of the debugging menu.

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And now we have to go through line by line inside of our code.

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So you should remember the three different options we have.

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Step into step over and step out.

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So let's go ahead and step into our main function.

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Now inside of our main function let's continue stepping.

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And then we should be able to print before division they're printed.

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And then we're going to step into our divide function.

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We're going to perform the division.

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And then we print our result.

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We reach the end of the scope for this function.

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And we go back to where the main function was called.

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And we're done.

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That's the end of this particular script.

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Now another useful thing with breakpoints is that we can add breakpoints while we're running the game,

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and that allows us to continue.

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Let's say we found a bug somewhere, and we want to figure out what exactly is causing the bug.

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So let's say this bug can repeat itself, and then we need to add a new breakpoint somewhere.

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Well, while the game is running we can add a breakpoint, and if we want it to print something in the

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console, we can totally do that.

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We don't have to stop play testing and then go in here and add another print statement in the code,

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and then go back and play test again.

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We can do it in real time.

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So as an example, what we're going to do is we're going to run this exact same code again.

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And right now we're currently at the calling of the main function.

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Now what I'm going to do is I'm going to add another breakpoint here.

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And let's go ahead and edit this breakpoint.

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And what we're going to do is we're just going to simply print out what the value of x and y is.

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So we can just do x comma y.

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And then we're going to have this uh continue execution I'm going to save that.

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So we just added a breakpoint while we're in the debugging menu.

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And then now let's just step into our code.

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So now we create x and y we go to the print statement.

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And as you can see it also printed out the value of x and y while we were in the middle of debugging.

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So that's another useful thing with breakpoints.

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We can just add them while we are in the process of debugging our code.

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For example, we can have this one print.

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Let's have this one print the results and we'll continue execution and we'll step over to get the result.

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There we go.

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It printed two, which was the result.

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And then we're going to call the print function again which printed two once more.

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And then we'll step out.

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And then our debugging process is over.

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But as you can see that's really cool.

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We can add breakpoints in the middle of debugging our code.

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We can't do that with regular print statements.

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Now we have even more debugging tools at our disposal.

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If we head to the view tab, we can open up another window called watch.

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And this one's a very interesting window because what it allows us to do is it allows us to watch the

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values of variables depending on a particular scope.

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And we can filter the scope out too.

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So if we hit this button right here that says all scopes, we can actually toggle what scope we want

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to look at variables.

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If it's going to be a global variable, an up value or a local variable.

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And then it also gives you descriptions of each.

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So a local variable is accessible only within the block of code where it's declared.

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And upvalue is a local variable that an inner function or a loop uses.

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So an upvalue would basically be, for example, if we had a variable up here called hello, that's

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equal to ten.

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If the current thread of execution is inside of our main function, we can access hello.

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But hello is not a global variable because we declared it to be local.

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But it's also not local to our main function.

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So therefore it's considered what we would call an Upvalue.

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So what I'm going to do is I'm going to delete these log points, and we're going to go back and run

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our code, and we're going to pay attention to this watch menu.

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As you can see right now we're in the debugging process.

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And we can see a whole bunch of different variables here.

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Here are some global variables which we don't really care about right now.

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So let's actually hide all of the global variables.

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So right now we have access to three different variables in the current scope we're at.

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So the current thread of execution is at this line.

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In this scope.

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And within the scope we can see three different variables.

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We can see our main function.

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We can see our example variable and we can see our divide function.

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And it tells us what the values are as well.

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So these two are functions.

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And our example variable has a value of 20.

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As we continue to step into the code you're going to see these values change.

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Right now we can only see divide because we're in the scope of the function.

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We're not able to see example var out here.

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We can only see divide right now.

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But once we create those two variables x and y now they appear inside of the variable section and they're

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both local.

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And you can also see that it declares that the divide function is an up value, which makes sense because

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divide is not a function that's a local to this scope, but it's also not a global function, so it's

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an up value.

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Now, another useful feature with this watch menu is we can go to this other tab called My Watches.

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And it allows you to enter in expressions.

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An expression is basically something like a Boolean expression or an arithmetic expression.

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It's just a result or a series of executions that produce some kind of result.

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So for example, an arithmetic expression would be x plus y and we can hit enter and look at that.

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It knows that it produces the value of 15.

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If we look at the values of x and y x is ten, y is 15.

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And therefore the result of this expression x plus y is 15.

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And we can do this while we're in the middle of debugging our code.

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We could do x minus y.

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We could do x times y.

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And as you can see it's going to show us each one of those values based on this expression and what

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is currently stored in these variables.

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Now let's say we want to see the expression of result plus x or something like that.

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We could do result plus X, but right now you're going to see that it says value is not found.

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And that's because we're currently on line number nine.

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And we haven't created the result variable yet.

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So let's continue stepping into our code.

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Let's perform the division.

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We'll create our result variable.

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And there you go.

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Now it has a value of result plus x.

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Because if we look at the variables tab we can see our result variable.

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And that is holding the value of two.

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So two plus ten is equal to 12.

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Another cool feature while we're in the middle of debugging is that if you hover your mouse over a particular

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variable like result and you keep it there, you're going to see a little window pop up and it's going

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to tell us what the value is stored in that variable.

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So as you can see result is two.

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How about x.

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Let's take a look at x x is ten.

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How about y y is five.

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Wow isn't that pretty nifty.

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These are all features that print statements can't give you.

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Sure, print statements are fast and easy to implement, but breakpoints give you so many more features

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that make debugging a breeze.

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Whether it's a logical error, whether it is a runtime error, using breakpoints can make the debugging

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process very fast, especially in conjunction with this watch menu.

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Let me slap in a few more expressions inside of the My Watch's menu, for example, is result greater

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than x?

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It's false.

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Of course.

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Result is not greater than x.

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Is x greater than result.

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Ah, that's true because x is ten, result is two.

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How about let's do a little bit more of a complex boolean expression.

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Is x greater than um let's say y and let's say result is greater than y.

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Oh that's false because x is ten, y is five, result is 12 and y is five.

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So this evaluated to false because not both conditions were true.

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So like I said there's a lot of different possibilities you can do with this.

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My watches section in the watch menu.

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Now one more debugging menu I'd like to show you is going to be something called the Script Analysis

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window, which you might have seen open down here.

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And basically what this script analysis window does is it'll show you any compile time errors or any

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warnings inside of your scripts, whether that's type annotation warnings, whether you made a mistake

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in your code somewhere, it's going to spit out those warnings in here and it'll tell you what script

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that warning is coming from.

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So as an example, let's say we made a really silly mistake with our main function and we forgot an

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end statement to close out the scope of the main function.

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Well, as you can see in the script analysis window, we have an error expected end to close function

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at line six.

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And instead we got end of file.

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So we can click that.

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It's going to highlight the error.

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As you can see the underline is right here.

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And it says the exact same error message.

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But it says we need to close a function at line six.

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So if we go up to line six here's our function and we can realize, oh silly me, I forgot to put an

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end statement here to close out the main function.

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And as you can see, the error is now gone from the script analysis window.

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I personally use the script analysis window while I am scripting, just in case any errors appear in

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other scripts while I'm modifying.

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Let's say a module that is used by other scripts when I am modifying that module.

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If any other script that's using it.

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Um, let's say an error occurs because I made a stupid mistake in the module.

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All of those errors will pop up inside of the script analysis window.

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So I can go ahead and take a look at what the issue is.

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00:13:35,120 --> 00:13:39,290
Here I have some example code that we're going to practice using breakpoints with.

230
00:13:39,290 --> 00:13:45,580
This code produces an intermittent error and that occurs when this random number generator produces

231
00:13:45,580 --> 00:13:46,960
a value of zero.

232
00:13:46,960 --> 00:13:52,210
And that's because we are not able to divide by zero when we divide a number by zero.

233
00:13:52,240 --> 00:13:57,370
This divide function is going to return a number called Nan, which is basically an invalid number.

234
00:13:57,370 --> 00:14:00,430
It's a number, but we shouldn't be using it in our code.

235
00:14:00,430 --> 00:14:07,060
And the issue with this is that if this returns Nan, when we try to set an index in our table that

236
00:14:07,060 --> 00:14:11,730
we're creating right here, and we try to set it with the index of Nan, we're going to run into a problem.

237
00:14:11,730 --> 00:14:16,920
And this only happens intermittently if the random number generator generates a value of zero.

238
00:14:16,920 --> 00:14:20,940
So what we're going to do is we're going to run this code and we're going to see how long it's going

239
00:14:20,940 --> 00:14:22,980
to take for us to reach an error.

240
00:14:23,700 --> 00:14:24,990
So we're going to run it.

241
00:14:24,990 --> 00:14:27,150
So far we're having no issues.

242
00:14:27,150 --> 00:14:28,260
Oh and there we go.

243
00:14:28,260 --> 00:14:30,060
We got an error table.

244
00:14:30,060 --> 00:14:31,680
Index is Nan.

245
00:14:31,680 --> 00:14:33,890
but our code is still continuing to run.

246
00:14:33,890 --> 00:14:39,920
And as you can see, this error is only happening when that random number generator produces a value

247
00:14:39,920 --> 00:14:40,760
of zero.

248
00:14:40,760 --> 00:14:47,660
So what we're going to do right now is we're going to pause the game because we need to start debugging.

249
00:14:47,660 --> 00:14:50,510
So as you can see the viewport is paused for debugging.

250
00:14:50,510 --> 00:14:53,630
We're going to hop into our script where the error is occurring.

251
00:14:53,630 --> 00:14:54,740
So we can click this.

252
00:14:54,770 --> 00:14:57,800
It's going to show us the line that the error is occurring.

253
00:14:57,800 --> 00:15:00,470
And we need to figure out why this is happening.

254
00:15:00,470 --> 00:15:05,480
So because we're in the debugging process, we are able to add in breakpoints right away to see what

255
00:15:05,480 --> 00:15:06,470
the heck is going on.

256
00:15:06,470 --> 00:15:12,380
So since we know the error is happening right here, let's add a breakpoint above just to see what the

257
00:15:12,380 --> 00:15:16,340
value of x and y is going to be and what the value of result is going to be.

258
00:15:16,340 --> 00:15:19,160
So let's go ahead and resume.

259
00:15:19,950 --> 00:15:21,450
We're going to hit that break point.

260
00:15:21,450 --> 00:15:24,570
And now we are at this line of before division.

261
00:15:24,570 --> 00:15:27,330
So let's go ahead and step into that.

262
00:15:27,660 --> 00:15:28,770
Let's see what we print.

263
00:15:28,770 --> 00:15:30,210
We print it out before Division.

264
00:15:30,210 --> 00:15:32,460
Let's continue stepping into the code.

265
00:15:33,090 --> 00:15:36,090
We're going to get a slash B and we're going to get a result.

266
00:15:36,120 --> 00:15:39,570
Now let's go ahead and open up our watch menu.

267
00:15:40,410 --> 00:15:43,680
And let's go ahead and take a look at what the current values are.

268
00:15:43,680 --> 00:15:47,570
So x is currently one, y is currently negative one.

269
00:15:47,570 --> 00:15:51,440
And our result is a value of negative one.

270
00:15:51,440 --> 00:15:53,720
Let's continue stepping into the code.

271
00:15:54,770 --> 00:15:59,510
Prints my table with a key of negative one.

272
00:15:59,510 --> 00:16:03,500
Now typically you don't want to have tables with negative keys but that doesn't produce an error.

273
00:16:03,500 --> 00:16:04,190
So it's fine.

274
00:16:04,190 --> 00:16:07,700
And let's just continue stepping through the code.

275
00:16:07,730 --> 00:16:11,210
Actually let's step into okay we're back at the breakpoint again.

276
00:16:11,210 --> 00:16:14,120
Let's see what the value of x and y is this time okay.

277
00:16:14,120 --> 00:16:15,320
They're both negative one.

278
00:16:15,320 --> 00:16:20,210
So we'll just continue stepping into the code see what result is.

279
00:16:20,210 --> 00:16:22,070
Result is one okay.

280
00:16:22,070 --> 00:16:23,090
No issues.

281
00:16:23,420 --> 00:16:25,340
We're going to continue going through the code.

282
00:16:26,300 --> 00:16:27,230
All right this time.

283
00:16:27,230 --> 00:16:30,830
Look at that x is negative one y is zero.

284
00:16:30,830 --> 00:16:35,060
So at this point if you're a good developer you should already recognize we're going to run into an

285
00:16:35,060 --> 00:16:35,480
issue.

286
00:16:35,480 --> 00:16:37,670
But let's continue stepping into the code.

287
00:16:37,670 --> 00:16:40,730
Let's perform our division and let's get our result variable.

288
00:16:40,850 --> 00:16:44,270
And result is actually negative infinity.

289
00:16:45,140 --> 00:16:49,670
So inside of our table, if we set that I don't think we're going to actually run into an issue okay.

290
00:16:49,670 --> 00:16:51,020
No we didn't run into an issue.

291
00:16:51,620 --> 00:16:54,020
So let's just keep going through the code.

292
00:16:54,050 --> 00:16:56,880
This time x is zero y is negative one.

293
00:16:56,880 --> 00:16:58,080
Let's keep going.

294
00:17:00,990 --> 00:17:03,030
Okay no issues so far.

295
00:17:03,300 --> 00:17:06,330
And as you can see x and y are now both zero.

296
00:17:06,570 --> 00:17:10,740
So let's see what result variable or the value we get in result.

297
00:17:10,740 --> 00:17:11,520
And look at that.

298
00:17:11,520 --> 00:17:14,610
Finally we have reached the crux of the problem.

299
00:17:14,610 --> 00:17:21,860
We have gotten Nan which is a problem because if we try to set that in the table, boom, we get our

300
00:17:21,860 --> 00:17:22,340
error.

301
00:17:22,520 --> 00:17:25,730
So now we have a pretty good idea of why this error is occurring.

302
00:17:25,730 --> 00:17:28,370
Let's go ahead and try to fix it in our code.

303
00:17:28,520 --> 00:17:35,420
Now one way we could fix it is we could basically say, hey, you know, if y is zero, let's just not

304
00:17:35,420 --> 00:17:41,120
do anything, but let's add in some error handling inside of the divide function.

305
00:17:41,120 --> 00:17:44,390
Or actually let's throw an error if we try to divide by zero.

306
00:17:44,410 --> 00:17:52,900
So if b is equal to zero, then we're just going to throw an error that we cannot divide by zero.

307
00:17:53,860 --> 00:17:55,690
And then we need to handle this error.

308
00:17:55,690 --> 00:17:57,970
So this is where Paul is going to come into play.

309
00:17:57,970 --> 00:18:00,310
So let's go ahead and do pcall.

310
00:18:01,060 --> 00:18:06,160
And we're going to call the divide function and pass x and y.

311
00:18:06,460 --> 00:18:08,230
And we need to get that result back.

312
00:18:08,230 --> 00:18:09,690
So let's return it.

313
00:18:09,810 --> 00:18:14,250
And then this p call is going to give us a boolean of whether or not we were successful in executing

314
00:18:14,250 --> 00:18:16,890
the code as well as our result.

315
00:18:16,890 --> 00:18:18,960
So now we can go ahead and get rid of this.

316
00:18:19,110 --> 00:18:25,860
And now what we can do before we set result inside of our table, we need to check if we were successful,

317
00:18:26,550 --> 00:18:28,680
if we were not successful.

318
00:18:28,680 --> 00:18:30,390
So let's do not.

319
00:18:30,960 --> 00:18:34,970
Then we're just going to return and do nothing.

320
00:18:35,060 --> 00:18:38,570
And maybe we can print out a message of the error.

321
00:18:38,570 --> 00:18:43,880
Maybe we'll put a warning here and we'll print out what the result was from this call, which should

322
00:18:43,880 --> 00:18:46,190
be the error message if we were not successful.

323
00:18:46,400 --> 00:18:51,230
And then let's go ahead and re-add our breakpoint right here and let's run the code again.

324
00:18:51,380 --> 00:18:53,840
So now we're back in the debugging process.

325
00:18:53,840 --> 00:18:58,810
Let's step into our code Okay, pretty lucky we got both zero and zero.

326
00:18:58,810 --> 00:19:01,030
So this should produce an error.

327
00:19:01,030 --> 00:19:05,620
So if we step into this we do that we're going to get our error.

328
00:19:05,620 --> 00:19:07,420
Boom error happened.

329
00:19:07,420 --> 00:19:10,270
As you can see success is set to false.

330
00:19:10,270 --> 00:19:15,820
And the result is what result is probably a string right.

331
00:19:15,820 --> 00:19:16,300
Yeah.

332
00:19:16,300 --> 00:19:20,290
There's our string value cannot divide by zero.

333
00:19:21,120 --> 00:19:24,630
So if we step into this we're obviously not successful.

334
00:19:24,630 --> 00:19:27,300
We're going to get a warning printed out in the console.

335
00:19:27,300 --> 00:19:28,680
Cannot divide by zero.

336
00:19:29,130 --> 00:19:32,670
And then we just return and we move on to the next iteration of the loop.

337
00:19:32,670 --> 00:19:38,400
And just like that, we have fixed our intermittent bug by handling it with a p call.

338
00:19:38,430 --> 00:19:38,970
All right.

339
00:19:38,970 --> 00:19:43,230
So the last thing we're going to do is we're going to hop into the Roblox documentation.

340
00:19:43,230 --> 00:19:50,210
And we're going to look around to see if a function in some kind of service needs p call to be used

341
00:19:50,210 --> 00:19:50,570
on it.

342
00:19:50,570 --> 00:19:55,970
Because as a Roblox developer, you need to be aware that there are certain functions in the Roblox

343
00:19:55,970 --> 00:19:58,550
API that may produce an error.

344
00:19:58,550 --> 00:20:03,290
Typically, these functions end with the word async, meaning asynchronous.

345
00:20:03,290 --> 00:20:09,130
Those functions make some kind of web requests to the Roblox servers and due to issues outside of your

346
00:20:09,130 --> 00:20:12,250
control, maybe there's some kind of internet issue or something.

347
00:20:12,250 --> 00:20:17,740
It might return some kind of HTTP error, and we need to be able to handle that using HTTP call.

348
00:20:17,740 --> 00:20:21,490
So let's go search through the documentation and let's go to our random service.

349
00:20:21,490 --> 00:20:23,440
Like let's go to the player service right.

350
00:20:24,130 --> 00:20:25,630
We'll go to the player service.

351
00:20:25,630 --> 00:20:32,170
And let's say we want to get the thumbnail picture of a player's head right.

352
00:20:32,170 --> 00:20:35,220
So let's see if there's a function in here somewhere for that.

353
00:20:35,580 --> 00:20:36,690
Ah yes here it is.

354
00:20:36,720 --> 00:20:39,240
Get user thumbnail and look at that.

355
00:20:39,240 --> 00:20:41,700
It says async and this function yields.

356
00:20:41,700 --> 00:20:47,670
So it says this function returns the content URL of an image of a player's avatar given their user id.

357
00:20:47,670 --> 00:20:52,620
So this function makes a web request and web requests can possibly fail.

358
00:20:52,620 --> 00:20:57,120
So this is an example of a function that we need to wrap an API call.

359
00:20:57,180 --> 00:20:58,770
So let's practice doing that.

360
00:20:58,770 --> 00:21:02,520
Let's grab the player service game, get service players.

361
00:21:02,670 --> 00:21:05,490
And every time a player joins our game.

362
00:21:05,490 --> 00:21:07,830
So we'll listen to the player added event.

363
00:21:07,830 --> 00:21:10,800
We'll connect a Lambda function to that.

364
00:21:10,800 --> 00:21:14,280
And this function is going to be passed the player that has joined our game.

365
00:21:14,850 --> 00:21:22,850
And we want to get the image ID of the thumbnail for this player's head so we can use the player service

366
00:21:22,850 --> 00:21:23,450
function.

367
00:21:23,450 --> 00:21:30,740
Get user thumbnail async I need to give it the user id of the player, so we can just do player dot

368
00:21:30,740 --> 00:21:31,520
user id.

369
00:21:31,580 --> 00:21:33,410
We need to give it a thumbnail type.

370
00:21:33,410 --> 00:21:36,530
So enum dot thumbnail type dot.

371
00:21:36,530 --> 00:21:37,730
Let's do a headshot.

372
00:21:38,300 --> 00:21:39,980
And what else do we need to pass to it.

373
00:21:39,980 --> 00:21:44,990
We need to pass the thumbnail size so we can do enum dot thumbnail size.

374
00:21:45,220 --> 00:21:48,370
And let's just do 180 by 180 pixels.

375
00:21:48,910 --> 00:21:53,050
And then let's go ahead and print out this image ID into the console.

376
00:21:53,050 --> 00:21:57,970
Now, it isn't likely that I'm going to run into an error because I'm not experiencing any network issues,

377
00:21:57,970 --> 00:22:01,510
but this is a function we should wrap in a p call.

378
00:22:01,510 --> 00:22:05,170
Otherwise if it errors, we're going to have problems in our code.

379
00:22:05,170 --> 00:22:11,500
So what we should do instead is we should call p Pcall, and we're going to pass a lambda function to

380
00:22:11,500 --> 00:22:11,980
this.

381
00:22:11,980 --> 00:22:15,550
And we're going to return the result of this function right here.

382
00:22:15,550 --> 00:22:19,780
So let's cut that and then let's paste that here.

383
00:22:20,170 --> 00:22:21,580
And we're going to return it.

384
00:22:21,580 --> 00:22:25,030
So this should return to us success.

385
00:22:25,030 --> 00:22:26,500
And then the result.

386
00:22:27,850 --> 00:22:35,000
And then if we were not successful then we can simply spit out a warning, which is going to be the

387
00:22:35,000 --> 00:22:35,870
error message.

388
00:22:36,380 --> 00:22:43,610
Otherwise, if we were successful, we can go ahead and, you know, print out our image ID, which

389
00:22:43,610 --> 00:22:45,650
is going to be equal to the results.

390
00:22:45,740 --> 00:22:48,200
I mean, technically I don't need this middleman variable.

391
00:22:48,200 --> 00:22:51,320
I could just print out results directly.

392
00:22:52,280 --> 00:22:55,400
And now let's go ahead and play test the game and see what happens.

393
00:22:56,450 --> 00:22:56,930
There we go.

394
00:22:56,930 --> 00:23:04,910
I got my IRL RGB thumbnail for my particular user ID and the width and the height.

395
00:23:04,940 --> 00:23:05,750
Pretty cool.

396
00:23:05,750 --> 00:23:10,820
And we can use this in like image labels and stuff to display, uh, the headshot of my character.

397
00:23:10,820 --> 00:23:13,070
But as you can see, no network issue.

398
00:23:13,220 --> 00:23:17,240
What I'm going to do is I'm going to artificially insert an error in here.

399
00:23:17,900 --> 00:23:21,380
We're just going to say some network error happened.

400
00:23:23,760 --> 00:23:25,560
And then let's go ahead and playtest the game.

401
00:23:25,890 --> 00:23:26,490
There we go.

402
00:23:26,490 --> 00:23:31,080
Some network error happened, but we did not halt the execution of the code.

403
00:23:31,080 --> 00:23:32,910
We did not have an error message appeared.

404
00:23:32,910 --> 00:23:35,220
We simply printed a warning into the console.

405
00:23:35,220 --> 00:23:40,770
And if you had any other code down here that still needed to execute, no matter you successfully got

406
00:23:40,770 --> 00:23:45,600
the user thumbnail or not, we are able to execute that code and we're not going to have any issues.

407
00:23:45,600 --> 00:23:49,670
There are a lot more functions in the API that we need to use pickle on.

408
00:23:49,670 --> 00:23:53,000
For example, get user id from name async.

409
00:23:53,000 --> 00:23:56,570
This is another asynchronous function that we should wrap an API call.

410
00:23:56,600 --> 00:23:57,800
Let's keep looking.

411
00:23:58,310 --> 00:24:00,620
Get name from user id async.

412
00:24:00,620 --> 00:24:03,050
Here's another function we need to wrap in API call.

413
00:24:03,290 --> 00:24:06,260
Get humanoid description from user id.

414
00:24:06,380 --> 00:24:11,380
This one doesn't have async in it, but this is a function that does yield.

415
00:24:11,380 --> 00:24:17,470
It's asynchronous, and because it does make a web request, we should also wrap this one in AP call.

416
00:24:17,500 --> 00:24:18,760
Same thing with this one.

417
00:24:18,760 --> 00:24:22,780
Get humanoid description from outfit id it also yields because it makes a web request.

418
00:24:22,780 --> 00:24:25,060
So we should wrap it AP call.

419
00:24:25,060 --> 00:24:26,140
Same thing with this one.

420
00:24:26,140 --> 00:24:27,640
Get friends async.

421
00:24:27,640 --> 00:24:29,560
Another one we should wrap in AP call.

422
00:24:29,560 --> 00:24:33,340
So there's actually a lot in the player service that we should be wrapping in a p call.

423
00:24:33,340 --> 00:24:35,910
Get character appearance info asynchronous.

424
00:24:35,910 --> 00:24:37,560
Another one we need to wrap in a p call.

425
00:24:37,590 --> 00:24:38,070
Let's see.

426
00:24:38,070 --> 00:24:40,740
Create humanoid model from user id this one also yield.

427
00:24:40,740 --> 00:24:46,170
So I assume that we should also use p call on this just in case because it does make a web request.

428
00:24:46,530 --> 00:24:48,240
Create humanoid model from description.

429
00:24:48,240 --> 00:24:51,630
Another one we should use p call on ban async.

430
00:24:51,660 --> 00:24:53,550
Obviously we should use p call on this one.

431
00:24:53,550 --> 00:24:57,390
By the way, this is a new function that you can have banned players, which is pretty cool.

432
00:24:57,770 --> 00:24:58,460
Team chat.

433
00:24:58,460 --> 00:25:00,680
That is a plugin property or something.

434
00:25:00,680 --> 00:25:02,840
So we don't need to worry about any of these ones.

435
00:25:03,320 --> 00:25:04,460
Get players.

436
00:25:04,460 --> 00:25:08,210
Obviously this is not a function you need to use p call on.

437
00:25:08,210 --> 00:25:08,960
It doesn't yield.

438
00:25:08,960 --> 00:25:10,340
That doesn't make any web requests.

439
00:25:10,370 --> 00:25:12,050
No need for P call on that one.

440
00:25:12,740 --> 00:25:16,940
And then we have some other functions we don't need to use p call on okay.

441
00:25:16,940 --> 00:25:17,510
Pretty cool.

442
00:25:17,510 --> 00:25:19,160
Let's take a look at another service.

443
00:25:19,340 --> 00:25:20,030
Alrighty.

444
00:25:20,060 --> 00:25:23,840
Here's another service that has a lot of methods or functions inside of it.

445
00:25:23,840 --> 00:25:27,140
We should be wrapping in P call and that's the marketplace service.

446
00:25:27,140 --> 00:25:30,920
Let's just go ahead and look through here and see if we can immediately find some functions.

447
00:25:30,920 --> 00:25:33,410
We should use P call on this one.

448
00:25:33,410 --> 00:25:33,860
We shouldn't.

449
00:25:33,860 --> 00:25:36,230
These are just prompting UI for players.

450
00:25:36,230 --> 00:25:40,460
There's no yielding and there is no network requests being made here.

451
00:25:40,460 --> 00:25:43,010
We don't have to handle any errors with these functions.

452
00:25:43,010 --> 00:25:48,550
But let's keep an eye out for any functions that are tagged as yielding, or if they have the word async

453
00:25:48,550 --> 00:25:49,900
in the end of their name.

454
00:25:50,710 --> 00:25:52,420
So let's keep looking.

455
00:25:52,450 --> 00:25:53,200
Oh, here we go.

456
00:25:53,200 --> 00:25:54,160
Here's one right here.

457
00:25:54,160 --> 00:25:55,900
Get developer products.

458
00:25:55,900 --> 00:26:02,260
Async returns a pages object which contains information for all of the current experiences developer

459
00:26:02,260 --> 00:26:02,830
products.

460
00:26:02,830 --> 00:26:04,240
This function yields.

461
00:26:04,240 --> 00:26:06,640
It's an asynchronous function and makes a web request.

462
00:26:06,640 --> 00:26:09,220
This is a function we should wrap in p call.

463
00:26:10,950 --> 00:26:11,760
Here's another one.

464
00:26:11,760 --> 00:26:13,260
Get product info.

465
00:26:13,290 --> 00:26:16,710
This one doesn't have the word async in its name, but it does yield.

466
00:26:16,710 --> 00:26:23,880
And it does make a web request to get information about a particular product in the Roblox catalog or

467
00:26:23,880 --> 00:26:24,750
something like that.

468
00:26:24,750 --> 00:26:27,480
So this is another function we should use Pcall on.

469
00:26:27,480 --> 00:26:34,700
And by this point, you should have a pretty good idea of what functions in the API you should be catching

470
00:26:34,700 --> 00:26:35,450
errors with.

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00:26:35,450 --> 00:26:35,660
Like.

472
00:26:35,660 --> 00:26:38,630
Here's another one you need to watch out for errors with this function.

473
00:26:38,630 --> 00:26:40,640
You need to watch out for errors with this function.

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00:26:40,640 --> 00:26:42,440
So there's a whole bunch of different ones in here.

475
00:26:42,440 --> 00:26:45,560
It's pretty easy to spot if it has async in the name.

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00:26:45,560 --> 00:26:46,580
Use P call.

477
00:26:46,580 --> 00:26:47,600
If it yields.

478
00:26:47,600 --> 00:26:54,020
You'll likely need to use p call if any of the definitions of the function talk about making web requests

479
00:26:54,020 --> 00:26:57,140
or anything, you should probably use p call.

480
00:26:57,140 --> 00:27:01,030
So that is all from me for this lecture.

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Yes, this lecture was likely a bit boring, but as a Roblox developer, it is super important for you

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to understand how to debug errors and how to handle errors using Pcall.

483
00:27:12,400 --> 00:27:17,230
This is one aspect of the development world that you cannot skip and you cannot bypass.

484
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You need to learn this stuff otherwise.

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Thank you for watching and I will see you in the next lecture.