Packing

[MUSIC] 0:00 Hi again, welcome to the final stage of functions, packing and unpacking. 0:04 We've talked a lot about the functions part of this course so far, 0:09 how are you feeling? 0:12 Do you feel confident in writing basic functions, passing arguments and 0:14 receiving returns? 0:17 If so, then keep moving forward to learn about packing and unpacking. 0:19 If not, then before moving on, try to review to content in the course so far. 0:22 Check out the Treehouse community, and practice by writing your own functions and 0:27 calling them to see how things work. 0:31 So what's packing? 0:32 Well, in the last section, we talked about passing multiple arguments to a function, 0:34 and how we receive each of those arguments into it's own parameter, or variable. 0:39 Packing expands on this concept and let's us do something potentially more useful, 0:43 and certainly more cool, let's dive in. 0:48 The basic concept of packing is compressing multiple values into 0:51 one tubal. 0:54 You can do this anywhere in your Python code, 0:56 but it's very commonly used when passing multiple arguments to a function. 0:58 Your function receives the multiple arguments and 1:01 packs them up into a single parameter. 1:04 This parameter now references a tuple where the elements of the tuple 1:06 are the many arguments passed to the function, kind of random right? 1:10 Well not so much, there are definitely going to be times in your python career 1:14 when you want to write a function that receives data, but 1:18 you're not sure what that data will look like ahead of time. 1:21 There's also going to be times when receiving all of your 1:24 arguments into one tuple, cuts down on the amount of code you need to write, or 1:27 drastically simplifies future steps. 1:31 Let's take a look, for now just follow along with what I'm doing, 1:33 don't worry about trying to code along with me. 1:36 So here we have a function called packer that receives multiple arguments, 1:39 packer prints each argument onto it's own line. 1:43 This is a pretty basic and pointless function but humor me, 1:48 we're just using it for demonstration purposes. 1:50 So I'm gonna write a call to this packer function where each argument is a string. 1:52 Now I'm gonna run this, just so 2:08 you can get a picture of what it looks like without packing. 2:09 Each argument has been received into its own parameter and 2:17 then it's printed out on its own line. 2:19 Now, if we wanted to take advantage of packing in Python and 2:22 pass these four arguments into one tuple, 2:25 we'd change our function definition to look more like this. 2:27 We'll get rid of each of these arguments, 2:32 and only use one, and then we can print args on its own. 2:36 Our function call is gonna remain exactly the same. 2:44 Now, when we run this, we'll see that each of our four individual arguments have been 2:48 converted to a tuple and are printed as such, let's take a look. 2:52 So what did we do here? 3:02 The secret is in the asterisk, 3:04 the little star at the beginning of the parameter name. 3:06 This star tells Python that we intend to pack all the arguments sent the function 3:10 into whatever parameter immediately follows the star. 3:15 This means when packer is called, and those four arguments are passed, 3:18 the function will receive them all into one table stored in parameter args. 3:22 args can then be used in the body of the function, just like any other parameter. 3:26 And because pupils are iterable if we still wanted each argument print on its 3:31 own line, we can still do that, but we'll use a loop instead. 3:35 Now I'll save, I'll come back down to my terminal. 3:50 I'll clear this out to leave a little more room, okay, so 3:53 when I run the file again, Cool. 3:56 As we iterate over args each element in the two ball is printed to its own line. 4:00 The parameter args with the asterisk before it is a very common pattern in 4:04 Python, you'll see the lot. 4:09 Let's dive into args a little more in the next video with a more practical example. 4:10