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Date: Fri, 18 Oct 2013 14:15:19 +0200
Message-ID: <CAH-PCH7QfvnUFC3X406D9riA_etGH8wYU_U=Ng9JGunZf_MS-w@mail.gmail.com>
To: J David <j.david.lists@gmail.com>
Cc: Joe Watkins <krakjoe@php.net>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b10c85354194104e902e3a5
Subject: Re: [PHP-DEV] Assertions
From: tyra3l@gmail.com (Ferenc Kovacs)

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On Fri, Oct 18, 2013 at 1:35 PM, J David <j.david.lists@gmail.com> wrote:

> On Fri, Oct 18, 2013 at 2:11 AM, Joe Watkins <krakjoe@php.net> wrote:
> > You have been provided very good rationale for the use of exceptions to
> > handle failed assertions, we'd all be grateful if you could stop
> derailing
> > the conversation.
>
> Wow.  Well, if you speak for everyone on this subject then go ahead
> and implement it.  Break all existing code everywhere that uses
> assert() and catches all exceptions.
>
> But:
>
> On Thu, Oct 17, 2013 at 6:51 AM, Julien Pauli <jpauli@php.net> wrote:
> > However, there is always the debatte about if a Core feature should thr=
ow
> > an Exception or generate an error.
>
> On Thu, Oct 17, 2013 at 7:45 AM, Sebastian Krebs <krebs.seb@gmail.com>
> wrote:
> > Actually if an assertion fails it means, that the application is totall=
y
> > broken and cannot get recovered. The use case you describe is more like
> > "validation".
> > This means, that even if it throws an AssertionException, when you are
> able
> > to catch it and recover the process, it means, that "assert" was the
> wrong
> > choice
>
> On Thu, Oct 17, 2013 at 8:01 AM, Michael Wallner <mike@php.net> wrote:
> > I tend to see it the same way. I think PHP's assert is derived from
> > C's assert, where ASSERT(3) says:
> >
> > "... assert() prints an error message to standard error and terminates
> >  the  program  by  calling abort(3) if expression is false ..."
> >
> > Where the important part is "terminates the program".
>
> On Thu, Oct 17, 2013 at 5:42 PM, Rowan Collins <rowan.collins@gmail.com>
> wrote:
> > Reading through the discussion, I think this point may deserve more
> > prominence: the problem with throwing an exception is that it is possib=
le
> > (and probably quite common) to have a catch block which catches *all*
> > exceptions. Throwing an exception from assert() tangles up any handling
> you
> > did want to do for failed assertions with the presumably rather differe=
nt
> > handling you want to do for runtime exceptions.
>
> are you sure you speak for "all" and that merely expressing an
> dissenting opinion is "derailing the discussion?"
>
> The feature you want is a useful new feature.  The only feedback I am
> offering you is to please consider adding it without breaking existing
> features, for example by calling it "expect" or "validate" instead of
> "assert."  The word "assert" is not innately magic.  Put "see also
> 'expect'" in the documentation of assert and if your functionality is
> truly better in all cases, people will naturally move from assert to
> expect and eventually maybe assert can be deprecated if PHP is really
> such a high-level language where it is not appropriate to have.  The
> only effect of calling this new functionality "assert" is to break
> existing code.
>
> Not to mention that since this approach does not break BC, doing it
> this way may allow the implementation of this feature sooner from a
> release standpoint.
>
> Likewise, if you separately want to enhance the diagnostic value of
> the existing assert functionality without breaking existing code, that
> would also, I believe, be most welcome.  But I don't pretend to speak
> for all so I cannot say for sure.
>
> If your response is "No, you are wrong because I say so," then so be
> it.  You may rely on my lack of further participation in the
> discussion, per your request.
>
> Thanks!
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
> Hi,

Personally I think that your argument was solid, and I'm fairly sure that
there are a bunch of code out there with your usecase:

try{
  // call a bunch of functions, which in turn calls a bunch of functions,
etc.
  // where one of the functions uses assert()
} catch(Exception $) {
  // report some generic error somewhere, or retry the calls a couple of
times before bailing out
  // or do nothing, or throw a different exception with or without setting
the previous exception to it
}

those kind of code would potentially swallow/silence the assert violation
or potentionally show a different error scenario what really happened, and
leave the developer confused how can he see that kind of error when the
same code works in production (where the assertions don't run).

using exceptions would also be less flexible than the current solution,
where you killed assert_options, so introduced a BC break for everybody
using that.

I also agree that maybe the new one should be added instead of replacing
the current(hence keeping BC), and later (when we have some feedback, and
maybe extended the new way with some of the old options) can decide to
deprecate the "old" assert infrastructure.

--=20
Ferenc Kov=C3=A1cs
@Tyr43l - http://tyrael.hu

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