<dict>.setdefault()

[John J. Lee]

Tino Lange <tl_news at nexgo.de> writes:
[...]
> This is not what I expected - why evaluate the second argument if it's
> not needed?
[...]

Because that's the way Python always does function calls?


> Is this really  by design?

Yes.


> If there's a complicated, expensive to
> calculate/build 2nd argument (maybe a function call) then it's also
> quite ineffective to evaluate it just to throw away...

Don't, then.  :-)  Use key in dict, or dict.has_key(key).


John