[Tutor] Function help

[Peter Otten]

Scott W Dunning wrote:

> 
> On Feb 23, 2014, at 1:12 AM, Scott W Dunning <swdunning at cox.net> wrote:
> 
>> I am VERY new to python (programming too).  I had a question regarding
>> functions.  Is there a way to call a function multiple times without
>> recalling it over and over.  Meaning is there a way I can call a function
>> and then add *5 or something like that?  I am trying to code an American
>> Flag using turtle for class so I’ll post the code I have so far below. 
>> As you can see towards the bottom I recall the functions to draw the
>> stars, fill in color and give it spacing.  I was wondering if there was a
>> way to cut down on all that some how?
>> 
>> Thanks for any help!

The example helps a lot! And of course this process of "cutting down", 
achieving complex tasks by doing simple things repetetively is what 
programmers do all the time. There is even a principle called "DRY" (don't 
repeat yourself) meaning that if you have to write something twice in your 
code you are doing it wrong.

Looking at

> fillstar(red)
> space(25)
> fillstar(red)
> space(25)
> fillstar(red)
> space(25)
> fillstar(red)
> space(25)
> fillstar(red)
> space(25)

a programmer would think "for loop" immediately

for i in range(5):
    fillstar(red)
    space(25)

and as this sequence occurs more than once in your code you should make it a 
function. For example:

def star_row():
    for i in range(5):
        fillstar(red)
        space(25)

If you want to make rows with more or less stars, or stars in other colors 
you could add parameters:

def star_row(numstars, starcolor):
    for i in range(numstars):
        fillstar(starcolor)
        space(25)

Your code will then become

star_row(6, red)
row(25)
star_row(5, red)
row(25)
...

which still shows a repetetive pattern and thus you can simplify it with 
another loop. You should be able to find a way to write that loop with two
star_row() calls on a single iteration, but can you do it with a single call 
too?