Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 3: Birthday countdown app
Lecture: Summary and debugging with PyCharm
0:00 So I hope you have a much better understanding
0:03 of how to work with dates,
0:04 and even how to work with other modules
0:06 that are built into Python by importing them
0:09 and using their name spaces and that sort of thing.
0:12 Let me show you one more feature about PyCharm
0:15 that I am sure you will find helpful
0:17 as you get into more complicated and complex applications.
0:21 And we can kind of use that to review what we built.
0:23 So PyCharm has a great built in debugger
0:27 and we can set a little break point right here
0:29 just by clicking on this section and if I run the app,
0:32 it won't hit the break point,
0:33 but if I hit the debug button, it will, so let's do that.
0:38 Now you can see our debug window down here,
0:40 you can see that we've got sort of watch window,
0:43 local variables, call stack, things like that,
0:46 we also have the console which is what we have
0:49 when we are doing the regular execution as well.
0:52 We can step over the current line using F8
0:56 or we can step into the function using F7,
0:59 or back out using shift F8.
1:02 So let's do F7 step in here,
1:05 here is our print header, and for the moment
1:07 let's switch over the console,
1:09 using and see as we step through, printing out,
1:11 very cool, step over,
1:13 now F7 to step into this get the birthday from the user
1:16 F8 to do some more steps
1:18 and down here we've got to enter our date,
1:20 so let's, we were using 1974,
1:22 if we go back to our debugger
1:24 you will see that we actually have this local year of 1974,
1:29 that is pretty cool, ok,
1:31 so let's take another step, go back to our console,
1:34 let's it just know we need some input
1:36 and we'll do one more step
1:38 print the date let's say 14th.
1:41 Over here in the debugger again,
1:43 you can see we've got these new values,
1:44 for some reason if we want to change this value,
1:47 come over here, we can actually set the value,
1:48 let's say the date was the 30th, something like that,
1:52 so we can actually go and change it,
1:54 you can see in the UI here, we can highlight it
1:56 because it's not code but you can see where these variables are defined,
2:00 what their actual values are, right,
2:02 these are the green ones from their natural value
2:05 and here is the one I've modified.
2:07 So, let's take one more step,
2:09 here you can see we've got our birthday,
2:11 now the birthday came back as a proper datetime,
2:13 we parse this so we went and we told the user
2:16 hey, enter your birthday
2:18 and we took the input, converted the integers,
2:20 so we used the class creation method,
2:22 use this method on the datetime module
2:24 that created instance of the datetime class
2:26 here you can actually see in the debugger
2:28 it's a datetime.datetime class, that's the type,
2:32 which is very cool, we are going to return this back,
2:33 so we'll step down, now our variables change,
2:36 now our birthday is this,
2:38 and now is its time, excellent,
2:42 so we'll step in here, one more time,
2:45 so we command the compute the days between dates,
2:47 and we got original date,
2:49 and now you can see the values up here
2:51 we are going to use the date 1 as right now,
2:55 and create another date,
2:57 using this constructor method again,
3:00 for the same year as this year
3:01 but the month and the day of the actual birth year.
3:04 And then what we saw when we do a subtraction here,
3:07 we actually get a time delta you can see there,
3:10 the curly braces little time delta
3:12 and we do that quick computation
3:14 we saw it's negative 59 days come back here,
3:17 and compute that and see the debugger
3:19 showing on the right of our code, all the various values
3:22 and last thing is to just print out those pieces and off it goes.
3:28 So excellent, what have we done,
3:29 we worked with the datetime module,
3:32 broke our code into reasonable small functions,
3:34 anyone of these little functions is super easy to understand,
3:37 and it's also easy to put together down here a main method.
3:41 I hope you learned a lot from building this birthday app.