I use narratives to learn stuff… and to teach, too
What’s a narrative? It’s a way of connecting events or facts in a form of a story
But I promised to talk about The Function Room…
My mental image of a computer program is that of a small creature working in a room.
When you start writing a program, the Main Room is empty except for some shelves and a small red booklet called “built-in”
Monty — that’s the name of the little creature doing all the hard work — will look around the room whenever you use any name.
more in the next toot
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At the start of the program, if you use a word that’s in the red booklet, Monty will know what to do.
keywords like while
, built-in functions like print
, these are the things in this booklet.
When you create a variable, such as:
day = "Monday"
Monty gets an empty cardboard box, puts the string "Monday"
inside the box and puts a label on the outside of the box which says day
Monty puts this box on a shelf in the Main Room
From now on, if you write day
in your program, when Monty looks around the room he’ll find a box labelled day
and he’ll get its contents—the string "Monday"
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However, he won’t go empty handed. He’ll take some data with him—the arguments you use when you call the function.
In the example in the previous tweet, Monty will take the integers 5
and 8
when he goes from the Main Room to the Function Room.
As Monty enters the Function Room, he’ll find two empty boxes at the entrance labelled first
and second
— these are the parameters from the function definition.
He’ll place the integer 5
inside the box labelled first
and the integer 8
in the box labelled second
. He will then place these boxes on the Function Room shelves.
Monty will then do whatever he needs to do in the Function Room.
When he’s done, he’ll return to the Main Room.
But once again, he won’t return empty-handed. He’ll take the contents of the box labelled output
with him since this is what you wrote in the return
statement.
Note that Monty does _not_ take the whole box labelled output
with him but only its contents. In the example above, this is the integer 13
What will Monty do with this integer as he returns to the Main Room and shuts the Function Room door behind him?
If the function was called like this:
result = do_something_clever(5, 8)
then he’ll bring another empty cardboard box, place the integer 13
inside it, and label the box result
. He places this box on the shelves in the Main Room.
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…but he won’t stay there long. Monty finds the name print
in the built-in red booklet which gives him directions to the print
Function Room which is elsewhere in Python City.
He’ll leave the Main Room to go to the print
Function Room, taking the integer 13
with him.
When Monty finishes from the print
Function Room, he’ll return to the Main Room and carry on with whatever instructions come next.
Usual caveat: analogies are not perfect. So don’t take them literally. Literally!
But, our brains react better to narratives rather than random facts. So I find that these ‘stories’ help me understand and remember this stuff so much better…
Hopefully it will help others, too.
If you want to read more on this analogy, you can read this:
https://thepythoncodingbook.com/understanding-programming-the-white-room/
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However, if the function call was just:
do_something_clever(5, 8)
then Monty doesn’t know what to do with the data he’s holding. So he’ll throw it away in the garbage bin so he can carry on with his work.
What if you write:
print(do_something_clever(5, 8))
Monty will go to the
do_something_clever
Function Room, do what he needs to do, and return to the Main Room holding the integer13
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