[Tutor] Demystification of Lambda Functions

[Peter Otten]

Steven D'Aprano wrote:

> Sometimes callbacks are particularly short and simple. Suppose you are 
> programming a calculator, and you have ten buttons 0...9 which all do 
> precisely the same thing: they add their own name to the calculator 
> display:
> 
> 
> for num in range(0, 10):
>     btn = Button(str(num), style="rectangle", 
>                  callback = lambda thebtn: display.add(thebtn.name)
>                  )
> 
> 
> Much better than having to pre-define ten functions and add them to each 
> of the buttons.

In this case the lambda obscures the fact that those ten functions are 
identical, so I'd prefer

def add_digit(button):
    display.add(button.name)

for num in range(10):
    button = Button(str(num), style="rectangle", callback=add_digit)