Is there a short-circuiting dictionary "get" method?

Peter Hansen peter at engcorp.com
Wed Mar 9 18:48:46 CET 2005


Dave Opstad wrote:
> In this snippet:
> 
> d = {'x': 1}
> value = d.get('x', bigscaryfunction())
> 
> the bigscaryfunction is always called, even though 'x' is a valid key. 
> Is there a "short-circuit" version of get that doesn't evaluate the 
> second argument if the first is a valid key? For now I'll code around 
> it, but this behavior surprised me a bit...

try:
     value = d['x']
except KeyError:
     value = bigscaryfunction()

get() is just a method, and arguments to methods are always
evaluated before being passed to the method, so the short
answer is "no, there is no 'version' of get() that will do
what you want".

-Peter



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