On 05Apr2015 03:34, Steven D'Aprano <[email protected]> wrote:
On Sat, Apr 04, 2015 at 11:49:08AM -0500, boB Stepp wrote:
widget = Button(None,
text='Hello event world!',
command=(lambda: print('Hello lambda world!') or sys.exit()))
That's either the most horrible misuse of lambda I've ever seen, or a
really cool and rather nifty trick. I'm not sure which :-)
I think it is misuse. When I need to run two functions like that I tend to use
a tuple:
lambda: (f1(), f2())
Since Python evaluates left to right, these functions are called f1 first, then
f2.
Using "or" introduces a reliance on f1 returning a falsish value. Dodgy and
unreliable. Not to mention conflating the supposed Boolean value computed by
the expression with the program's purpose.
Like others, I agree it is generally better to define a function more normally
and just name in instead of inlining a lambda. But sometimes (rarely) that
makes for harder to read code structure (though easier to read function
internals).
Anyway, faced with a desire to use a lambda here, I would choose a tuple.
Cheers,
Cameron Simpson <[email protected]>
This is my simple religion. There is no need for temples; no need for
complicated philosophy. Our own brain, our own heart is our temple; the
philosophy is kindness. - Dalai Lama
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