[Python-Dev] PEP 8: Discourage named lambdas? (original) (raw)

Alex Martelli aleaxit at gmail.com
Sat May 3 17:24:54 CEST 2008

On Fri, May 2, 2008 at 11:32 PM, Mike Klaas <mike.klaas at gmail.com> wrote: ...

Sorry, that was a bad example. It is obviously silly if the return value of the function is callable.

...and yet it's exactly what keeps happening to lambda-happy programmers -- in production code as well as examples, and in major/famous projects too. E.g., a simple google code search shows many Zope versions containing "Bucket=lambda:{}" instead of the obvious "Bucket=dict", Chandler with an intricate t = threading.Thread(target=lambda x=activePort:testcon(x),verbose=0) instead of t = threading.Thread(target=testcon, args=(activePort,), verbose=0) SQLAlchemy with "callable_=lambda i: self.setup_loader(i)" instead of "callable_=self.setup_loader" ... apparently the existence of lambda may easily blind one to the fact that one can simply pass a callable. I guess that's inevitable (given lambda's existence... and human nature;-) and about on the same plane as another hatefully redundant construct I find myself having to beat upon over and over in code reviews:

if : result = True else: result = False return result

vs the simple "return " [[or bool() if it's actually mandatory to return a bool and can't be relied upon to produce one]].

Alex

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