Perhaps the OP can look into Python macro libraries to get the wanted syntax?
https://github.com/lihaoyi/macropy On Tue, Jan 16, 2018 at 2:35 PM, Paul Moore <p.f.mo...@gmail.com> wrote: > On 16 January 2018 at 17:36, Sylvain MARIE > <sylvain.ma...@schneider-electric.com> wrote: > > (trying with direct reply this time) > > > >> Why do you do this? What's the requirement for delaying evaluation of > the condition? > > > > Thanks for challenging my poorly chosen examples :) > > > > The primary requirement is about *catching* > > unwanted/uncontrolled/heterogenous > exceptions happening in the underlying functions that are combined together > to provide the validation means, so as to provide a uniform/consistent > outcome however diverse the underlying functions are (they can return > booleans or raise exceptions, or both). > > > > In your proposal, if 'is_foo_compliant' raises an exception, it will not > be caught by 'assert_valid', therefore the ValidationError will not be > raised. So this is not what I want as an application developer. > > Ah, OK. But nothing in your proposal for a new statement suggests you > wanted that, and assert doesn't work like that, so I hadn't realised > that's what you were after. > > You could of course simply do: > > def assert_valid(expr, help_msg): > # Catch exceptions in expr() as you see fit > if not expr(): > raise ValidationError(help_msg) > > assert_valid(lambda: 0 <= surf < 10000 and is_foo_compliant(surf), > help_msg="surface should be 0=<x<10000 or foo compliant") > > No need for a whole expression language :-) > > Paul > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Juancarlo *Añez*
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