Python Lambda Expressions

maxmanders — Thu, 19 Nov 2009 14:52:55 +0000

I’ve been writing a small Python/Tk application and until recently was having trouble with menu item callback functions. I have a series of menu items, all of which do much the same thing, but within the context of an item-specific ID. Therefore it would make sense to have a generic function that takes some parameter to determine what to do.

However, when adding a menu item and callback, e.g.

menu.add_command(label = someLabel, command = someCallback)

you must pass in the name of a function, rather than a function call. To get around this, I used a lambda function to pass in a previously defined value to a callback:

id = some_value
menu.add_command(label = someLabel, command = lambda id=id: someCallback(id))

Max Manders » Python

Python Lambda Expressions