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David Ton-Lai
3,268 PointsNot sure about "menu[choice]()"
I understood Kenneth's explanation for most of the code, but I'm not sure why there are parens after menu[choice](). I know it's a dictionary, so menu[choice] is refers to the key in the dictionary. Is the () a special attribute of OrderedDicts?
2 Answers
Chris Freeman
Treehouse Moderator 68,457 PointsThere is a bit of trickery here that shows off the power of "functions as first class citizens". If the dictionary menu is populated with values that are functions, then menu[choice] will return one of these functions.
Since functions can be passed around just like variables, the function can be returned by menu[choice] as a 'non-executed object which can subsequently be executed by simply added the parens () to signify executing the function.
A longer way to write this would be:
some_func = menu[choice]
some_func()
# or combining into one statement:
menu[choice]()
Jonathan Prada
7,039 PointsExactly what i wanted to know, that is cool
David Ton-Lai
3,268 PointsDavid Ton-Lai
3,268 PointsWow that's cool, I hadn't considered that. Thanks for clearing that up Chris!