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Re: List comprehension for testing **params

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On 11/11/12 17:18, Steven D'Aprano wrote:
> but that leaves you with the next two problems:
> 
> 2) Fixing the assert still leaves you with the wrong exception. You 
> wouldn't raise a ZeroDivisionError, or a UnicodeDecodeError, or an IOError 
> would you? No of course not. So why are you suggesting raising an 
> AssertionError? That is completely inappropriate, the right exception to 
> use is TypeError. Don't be lazy and treat assert as a quick and easy way 
> to get exceptions for free.

I'd say that it depends on whether the dictionary/kwargs gets
populated from user-supplied data (whether mail, a file, direct
input, etc), or whether it's coder-supplied.

I like to think of "assert" as a "hey, you bone-headed programmer,
you did something that violated conditions for using this code
properly!" and as such, entirely appropriate to use in the
coder-supplied case.  This rolls into...

> 3) Asserts are not guaranteed to run. Never, never, never use assert to 
> test function arguments supplied by the caller, because you have no 
> control over whether or not the asserts will even be called.

where, once the programmer is satisfied that the code runs, meeting
all the appropriate tests/assertions, the assertions can then be
turned off (if one really cares that much; can't say I've done it
more than a couple times, mostly out of experimentation/testing to
see if it made any grave difference in performance).  I think you
intend this in your

> Or for testing things which "can't possibly fail". But of
> course, since what can't go wrong does, you sometimes still want
> to test things.

-tkc

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List comprehension for testing **params Cantabile <cantabile.03@wanadoo.fr> - 2012-11-11 23:24 +0100
  Re: List comprehension for testing **params Ian Kelly <ian.g.kelly@gmail.com> - 2012-11-11 15:56 -0700
  Re: List comprehension for testing **params Tim Chase <python.list@tim.thechases.com> - 2012-11-11 16:49 -0600
  Re: List comprehension for testing **params Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-11-11 23:18 +0000
    Re: List comprehension for testing **params Tim Chase <python.list@tim.thechases.com> - 2012-11-11 18:21 -0600
      Re: List comprehension for testing **params Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-11-12 07:32 +0000
  Re: List comprehension for testing **params Terry Reedy <tjreedy@udel.edu> - 2012-11-11 18:37 -0500
    Re: List comprehension for testing **params Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-11-11 23:41 +0000
  Re: List comprehension for testing **params Cantabile <cantabile.03@wanadoo.fr> - 2012-11-12 00:53 +0100
  Re: List comprehension for testing **params Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-11-12 11:48 +0100
    Re: List comprehension for testing **params Cantabile <cantabile.03@wanadoo.fr> - 2012-11-12 23:25 +0100

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