Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 4: Journal app and file I/O
Lecture: Documenting the journal module with docstrings

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0:00 Let's make our journal module just a little nicer to work with.
0:03 So if I come over here and I look at this journal and I hit F1,
0:06 you'll see that PyCharm can kind of guess
0:09 hey I think this is returning a list but it's all that we really get.
0:14 Now, if I look at some built in like print it will give me decent documentation
0:19 like hey here is all the values, here is how you typically use it,
0:23 here is a link to the documentation and so on.
0:26 We would like our journal code to look like that
0:28 and it turns out it's super easy.
0:30 So if we come over here and we enter a string,
0:35 on its own line right by itself here,
0:38 that will actually be the documentation
0:41 and there is a format that lets you describe the return values
0:44 and the parameters and expectations and everything.
0:47 So, one way that we can create the string,
0:50 let's just take a break for a minute,
0:52 call it S is we saw we could put single quotes like this,
0:56 or we could put double quotes like this,
1:01 but the third way is to extend that to be sort of a string literal across multiple lines
1:05 I could say S = ' ' ' and hit enter, right,
1:08 this is multi line and close it off like that,
1:16 and that's actually a string with one, two new lines
1:19 and then this and then a new line,
1:22 so you can have this sort of richer strings in that way
1:25 and that is the style we are going to use, to document this here.
1:28 So we are going to come over here and say ' ' ' and when I hit enter,
1:32 PyCharm is actually going to help me out.
1:34 Notice it says, ok it looks like you are trying to add a docstring,
1:37 so we are going to have a parameter called name
1:41 and we'll give you a chance to describe that
1:43 so this will be the base name of the journal, to load,
1:47 and it can talk about the return value
1:52 a new journal data structure populated with the file data,
1:58 something like this and then at the top
2:00 we have the general method summary
2:02 and so this method loads and say creates and loads a new journal.
2:10 So let's go over to our program and do that little trick again we had,
2:14 so I can come over here and I can look at this,
2:17 and hit F1 and now it pulls it up and says
2:20 this method creates and loads journal and guess what
2:22 the name parameter, this is the base name of the journal
2:24 and the return value that's a new journal, Woho!!.
2:27 So now you have proper documentation.
2:30 Now if we come here to Python console and we say import journal,
2:34 I can write things like help (journal.load) and when I hit enter
2:39 you can see just like we got into UI there
2:42 we also get the text version so if you are working in the console or the terminal
2:45 the sort of standard help also uses the same docstrings.
2:49 Now I did notice that PyCharm was suggesting that we should use 3 double quotes,
2:55 so let's go and make it happy, and do that here like so, perfect.
3:00 Now, of course in the real app we go right this for save
3:02 and all the other pieces, we can even do this for the module itself
3:06 say this is the journal module,
3:10 and now if I were to come down here and do that import again
3:13 or come over here to the top and look at the journal,
3:17 I can ask for help and it actually gives me module level documentation as well.