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Python Python Basics Functions and Looping Functions

1,552 Points

the "( )" after "text.upper( )"

English is not my first language so sometimes I keep scrubbing the video to understand what Craig is saying, and now I think I didn't get why a blank "( )" is needed after the "text.upper( )".

Why is this needed again? It also helps if I can be directed to a video where he discusses about it :)

1 Answer

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

The parens () signify that the method should be called. Without the parens, text.upper is a reference to the method.

In Python, methods and functions are “first-class citizens” and may be referenced directly, assigned to a variable, and passed to other functions when the parens are not used.

Post back if you need more help. Good luck!!!

the follow-up question I have is, I get that the functions get priority but why not still use parens simplicity ? or is there more to it?

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

There are solid use cases for executing the function or method vs getting just a reference to the function or method.

The parens are used when arguments are passed to the function during its execution. If no arguments are needed, then a pair of empty parens are used to say “execute, but no arguments are provided.”

With no parens, no execution of the function occurs. Instead a reference to the function is used.

One example,

def change_text(text, func):
    return func(text)

print(change_text('abcde', str.upper))
print(change_text('abcde', str.capitalize))



Another less obvious use of passing a function is decorators. A decorated function is passed as an unexecuted function and an updated unexecuted function is returned in its place.