Returning values from a lambda
wtanksle at dolphin.openprojects.net
Fri Nov 16 18:45:18 CET 2001
On Fri, 16 Nov 2001 12:07:05 +1000, John McMonagle wrote:
>William Tanksley wrote:
>> On Fri, 16 Nov 2001 10:36:06 +1000 (EST), John McMonagle wrote:
>>>I wish to return values from a lambda function which is bound to the
>>>Tkinter button command option. For example,
>> Wait a second. You don't want to return values; you want to modify
>> variables. There's a HUGE difference; lambdas can do the first, but they
>> don't support any of the syntax to do the second.
>> The solution is to not use a lambda. Just define a function which
>> modifies the variables you need, and pass that function's name in place of
>> the lambda.
>But I need to use a lambda in order to pass arguments to the function.
You can wrap a lambda around the function, if you'd like; or you can
access the variables directly in the function itself (it helps to be using
the new scoping code, but that's not essential).
>>> return a+b, a*b
>> def operations(a,b):
>> x = a+b
>> y = a*b
>Indeed I could do it like that, but I would need to define globals for x
>and y. Can this be done without using globals ?
Your original example used x and y. My reply, therefore, used them as
well. What do you want me to use?
The best way is to communicate through an object. Try something like this:
r = MyButtonResponse()
b = Button(..., lambda r=r: setButtonClicked(r)
'r' is the response object, contains the needed returns, and can be
examined at your convenience. You could also have it be a member
variable, of course.
-William "Billy" Tanksley
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