print statement in lambda expression

[Brian Quinlan]

> I just recently found that I couldn't put a print statement in a
> lambda expression as a binding in Tk. Could someone explain why?
> 
>     ie.
> 
>     b1 = Button(frame, text="Message", command=lambda: print
"message")
> 
> If I replace print with sys.stdout.write, it works fine. I don't
> follow why.

'print "message"' is an statement, not an expression, and lambda
expressions must be, well, expressions :-)

All function calls are expressions so sys.stdout.write will work.

Cheers,
Brian