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Date: Mon, 27 Nov 2017 07:06:39 +0300
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Subject: C++-like function-try-block proposal
From: enclaved@Safe-mail.net

Greetings!

I have been referred to this mailing list by https://wiki.php.net/rfc/howto
as the first step to propose a language change.  I first tried to register
on wiki.php.net as per php-src/README.SUBMITTING_PATCH in order to actually
make an RFC, only to be given an error:

  Writing /srv/web-wiki/dokuwiki/conf/users.auth.php failed

I am proposing a patch (see attachment) to bring C++-like function-try-block
shorthand syntax (http://en.cppreference.com/w/cpp/language/function-try-block)
for whole-function try-catch-finally blocks:

  function fuu($foo, $bar): void try
  {
    may_throw($foo);
    may_throw($bar);

  } catch (FuuException $e) {
    echo $e->getMessage();
  }

Since PHP is partially influenced by C++, I believe this syntax would be
a meaningful step in making PHP a little bit more intuitively compatible
with C++ practices, which may prove useful for people who come to PHP from
the C++ world (such as myself.)  The expected benefit is PHP becomes yet
more familiar and comfortable for C++ programmers.

Also, this syntax saves us one set of curly braces and an indentation level,
allowing for more compact and expressive functions, and especially closures:

  $s = preg_replace($re, $s, function (array $m): void try {
    return find_replacement(...$m);
  } catch (Throwable $e) {
    return $m[0];
  });

In addition to the syntactic sugar, I would like to outline another possible
merit: the very fact of such a shorthand construct existing may encourage
programmers to write functions with a consistent approach to exception handling
at whole-function level.  Each such function becomes a self-contained code unit
tightly coupled with its exception handling logic, the programmer's intent
clearly outlined by the use of the proposed construct, thereby facilitating
code clarity and integrity and promoting a stricter and more rigid code style.

The proposed patch makes purely cosmetic modifications to zend_language_parser.y
grammar to augment plain functions, class methods, and closures to accept
try-catch-finally blocks as their bodies in addition to regular compound
statements.  It amounts to just a handful of lines and entails no API changes.

I submitted my patch via the bugtracker: https://bugs.php.net/bug.php?id=75576

Please share your thoughts.

--Alexei Gerasimov