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Oftentimes as you are writing code you'll find pieces of code that you want to

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reuse in different projects. For this you'll want to write here own modules.

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So let's take a look at how we do this.

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For example, if this is my homepage and if you look down at the bottom of the

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page you'll see that it tells the time and it says it in words.

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It says it's twenty past three.

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Now, I did this with a Python module, and we're going to take a look at that

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module, and here it is.

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Now, the point of this is to show you how to put the code into the module.

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We'll look at the details of the module in another lesson.

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But for now let's see that it has this class numwords.

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But for now let's just look at from the perspective of how we put the code into a module.

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So you'll notice that it has this class numwords, and this formats a number into words.

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And it has this other class saytime_t that inherits numwords and that

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class is for formatting the time as words.

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And then it has a special version of saytime as a wrapper for using a time object.

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And it has a main function, so that it can be run from the command line.

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And it has a test function for testing.

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And so all of this is put in a normal file and really there is nothing

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special about the file.

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In fact, if I run it-- we'll go ahead and do that.

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You see that it gives the time right now, twenty-eight til five.

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It can also be run with an argument that hasn't run these tests.

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And in Eclipse, so a little bit of a production to get it to do that, to come

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over here and give it an argument, say test, and Apply and Run, and then it runs

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it in test mode.

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And you'll see if I do that from the command line, I just give the word test on

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the command line, and it runs all of these tests.

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It tests all the numbers and it tests the time.

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I'd like to do things this way.

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You can also use the unit testing module that comes with Python.

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And so I have a lot of results that I could look at.

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So the module itself you just write it like you write a normal script.

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You write your script and in the process you write whatever classes you're going to write.

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And you think about how it will be accessible from the outside world.

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And then when it's time to use it as a module you'll notice down here at the

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bottom it has this if _name_ pattern, we've seen this before.

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And that prevents the main code from being run when it's imported as a module.

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So I don't have any code that's outside of a function.

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And that's generally true when I write a script any way.

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And here is the script on my web site.

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It's a very short script.

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That's the entire thing.

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And all it does is it imports time, because it grabs the time as a localtime

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variable, and it also wants to be able to format that time so that it can format

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the date and time as well.

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And it imports the saytime module and it calls that here.

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It says "In Phoenix Arizona, it is now," and it has the saytime words.

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And it has the formatted date, on day of the week, and the day, month, and year.

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And so when we run that you'll see it has the CGI header because this is

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included in a page as a server side include.

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And it says, "In Phoenix, Arizona, it is now," and it gives the time, twenty-six

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til five, on this date.

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And so when you have code that you want to reuse you're going to want to put

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it in a module and when you put it in a module it's really just like writing a normal script.

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You just need to be careful that you don't have any code that's outside of a

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class or a function, and you want to have this pattern down here at the

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bottom for running main.

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So that you have some way to test it or as I do with this one, to actually

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just use it as a script.

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Let's go ahead and take that out. It's still got the argument in there.

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So that when it's not run with the test argument it just runs it as a script and

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it gives the time so you can include it in a shell script or you can use it in a

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lot of different ways.

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So I'm looking for flexibility when I do this.

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But that's essentially all there is to it.

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You just put your classes in there, set it up with the pattern at the bottom so

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that it only runs main when it's not imported, and so it doesn't do that when

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it's imported and then your class becomes available to other scripts.

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And you'll see a lot of examples of this as we go through the projects later

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on in the course.