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In this lecture, I'd like to show you some of the other capabilities of Sony in particular relating

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to debugging that a lot of people are asking about.

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I've got to say that these features are not really available for micro python programming on the episode

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of two, but they are available for general purpose, Python and for desktop version of Python.

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And I'm going to use that for examples that are coming up.

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Again, these are not features that we are going to be using later on in this course, but things that

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people do ask about.

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And I just wanted to make sure that you've got a good understanding of the Sony ID, Ed, before we

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get on with my python.

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So I have already opened up the via Ghosheh and Stack Winderlich.

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You can do that by going to view and choose the window that you want to open up the service, for example,

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the program tree that you can see down here.

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And let's have a look at your object, inspector and so on.

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I'm not going to go through all of them because then we are going outside of the scope of this course,

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which is to focus on micro python.

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And before I start with my small demonstration, I also want to point out that if you go to these Thorney

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dot org website, it's a very homepage.

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There's a demo video here which I have mentioned previously.

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You should really take a look at it will give you a really good overview of those features.

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And I'm also going to touch upon in this lecture.

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OK, so I'm going to turn off the object inspector and the program that really need it.

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And I'm going to switch my targeted interpreter to the default one, because, as I said, these features

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don't work with the especially to micro python version.

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So now we are running Python three point seven point.

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And I got a little program here that just adds to numbers of code number one.

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And number two, just a couple of arbitrary random numbers.

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You can also use the input function to allow you to enter those numbers during runtime.

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But let's keep things simple then.

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I've got a calculation happening here.

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The result goes into the some variable and print out the results onto the show like this.

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And I'm using the format function to talk more about this in Section five, which is fairly detailed

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introduction to Python.

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So there were better details about what this does.

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What is important right now is what the output is.

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So you run this program and you see that the output is just the sum of the calculation with a bit of

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information about what was calculated by the component of the calculation.

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Now, see what happened as soon as they executed the program is that the variables tab became populated

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with the numbers you can see here that have got the value idea, which is this is a memory location

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where no one is stored.

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And number two, and some also have the heap.

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Memory in the stack is empty and a hidden memory is where both he and Stack are stored in Ram Python

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in particular uses heap and stack differently.

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So it said both are part of their end.

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But in memory, Python is going to store the global variable she can see here.

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No one is a global variable and stored at this remote location.

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c.B zero, and that matches this idea here in the heap, which has this value one point five as it was

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assigned here, and line number three in the script.

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And similarly, number four line declares initializes variable number two, which you can see here.

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This is its value add in RAM, which is right here in the heap.

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Again, here is where Python stores its global variables.

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You've got some which was created later and its content are the result of the addition between number

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one and number two.

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We don't have anything in the stack because we don't have any functions.

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So let me show you an alternative of this little simple program.

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So here I've got the exact same thing happening, but now I've got a function declared called add numbers.

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And again, don't worry about the details.

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I'm going to talk about how to create functions in Section five of this course.

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But you'll see that we've got the global variables.

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We've got some variable created here, and then we've got a call to the function at numbers.

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So essentially the program jumps from here to here and then we're going to line number five and execute

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it.

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Now, if I run this program, see what happens.

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So after the execution of the program, one thing that we didn't really see was what happened in this

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attack, if at all.

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So this attack, as I said earlier, is where Python keeps track of its position in the program.

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Trees are especially useful when we have to go from one part of the program and continue with the execution

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of the program inside a function.

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So for Python to know where to return once the execution of the function is complete, it needs to keep

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track of the origin of the call inside the stack and to be able to see the start getting populated.

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I'm going to use the debug function first.

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I'm going to have a little line stop here.

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Just double click on the line where I want the execution to stop temporarily and then I'm going to click

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on the current screw button and that will start executing the program.

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But they will stop at the location where I've got the red dot, the stop line, and you can see that

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I've got my variables here, the global variables.

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I've got my head exactly as we did earlier.

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Now we've got an additional component in the heap.

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We've got the function ID numbers.

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So the program does know about it.

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And I can continue the execution of the program by using one of those patterns here.

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So step over, step into and step out, step over allows me to move on to the next line of the program

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without actually drilling in into the individual components that make up this line of code instead of

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going stepping over.

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I'm going to go step into to explain more about what I'm talking about here, to remember that we are

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now executing line 15.

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And I'm going to step in to and you can see that now with step into the execution continues into the

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right side of the equals sign.

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And if I click on Step into again, it drops further into the first component of this edition.

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And it will evaluate that you can see that it will change it into its I.D., so Vago no one now has

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been replaced in the code itself with its value I.D., which you can see the variables tab.

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And also in the caps, you can see it's actually assigned value.

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Do one more step in two and then it goes over to the other side and have a look at the number.

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And again, you can guess if I click on it again, it's going to into the number and replace it with

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its eyeteeth.

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But instead I'm going to go and do a step over and that is going to skip it and start exiting.

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And until eventually the whole thing, the sum of these two numbers is replaced by the idea where those

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numbers are stored, which is B three zero seven point eight.

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And it's just about again, it's going to jump into line nineteen.

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Now, look what happens here.

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As soon as I went into line 19, what is the call to the add numbers function?

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The stack keeps track of that.

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The stack now keeps track of where I'm going to jump into another part of the program, which happens

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to be a function so that this is where I'm going to return or the problem is going to return to once

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the function execution is complete and it's going to step over there and be finished.

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So it's not going to go into the function because I did a step over when to do one more thing here.

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And I'm going to say Trent finished

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like that and I'm going to execute again.

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And using the debugger this time, I'm going to go for that over for the first time and then I'm going

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to do step into four to do that.

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I'm going to open up the stack.

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When you can see that the module line 19 is in the first position of the stack them I'm going to step

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into now drilling into the function.

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And now this is interesting.

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You see that a new window popped up because now we have drilled into the add numbers function.

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So a new window popped up to show us what is happening inside that function.

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And you can see there are another entry has been made into the stack.

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This is now line five, which is the line that we are executing right now so as to step into again,

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see drilling into the individual components and replacing them with the ideas in the heap that contain

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the values for those variables.

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So those that adhere as they are being executed and evaluated.

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And so on, so the whole print statement and its parameter is replaced by a single location of single

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idea, I should say, right here, eight four zero eight if you're like this, which is where the string

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of the result message is stored.

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So one more, OK, finished, so that's done so you can see that we are now coming back from the stack

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into the main part of the program.

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So they stack entries now only contains like 19 because we are done with the python is really done with

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the execution and the variation of the function.

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So let's do one more.

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Actually, I'm going to go for a step over now and print up finished and we done.

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So this demonstration just wanted to show you what kind of work you can do with the additional views

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and features that are available here under The View menu.

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Again, we're not going to be able to use these features in our micro python programming on the specific

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two, but they are available, if you're interested in general purpose, desktop or C Python programming.

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The debugger that we saw in action here is actually a Python project called the Bird's Eye.

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So you can find project documentation for Birds Eye here, including a tutorial on how you can use it

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and what else you can do with it.

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I've only scratched the surface.

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It's a very interesting and useful python debugger that if you're interested in doing some more complicated

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Python programming, is good to know how to use that time.

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OK, now, in the next couple of lectures, like to show you how to do simple micro python programming

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tasks with the BBC Microgrid and the Raspberry Pi.