Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:110211
Date: Tue, 19 May 2020 09:04:43 +0200
To: "Peter Stalman" <sarkedev@gmail.com>
Cc: "PHP internals" <internals@lists.php.net>
Message-ID: <1722bbfa250.1200d3c6a254667.725500817558436494@manuelcanga.dev>
In-Reply-To: <1722bb5aeba.efaf5e2a253261.3998926174950017220@manuelcanga.dev>
References: <f9109d72-f3d3-5b12-16bb-9ec03d164cf4@ralphschindler.com> <85C8412B-B04A-4853-8C4C-E270FCB35EEE@getmailspring.com> <CAPrKfG6tr6MmLCBBds7nSUnc7SUno+uEPaAcBzRFhWw+VPAttw@mail.gmail.com> <1722bb5aeba.efaf5e2a253261.3998926174950017220@manuelcanga.dev>
MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Importance: Medium
User-Agent: Zoho Mail
Subject: Re: [PHP-DEV] Proposal For Return-If / Early Return / Guard Clause
 Syntax
From: php@manuelcanga.dev (Manuel Canga)






 ---- En mar, 19 may 2020 08:53:46 +0200 Manuel Canga <php@manuelcanga.dev>=
 escribi=C3=B3 ----
 >=20
 > Hi, Internals,
 >=20
 >=20
 >=20
 >  ---- En dom, 17 may 2020 06:33:51 +0200 Peter Stalman <sarkedev@gmail.c=
om> escribi=C3=B3 ----
 >  > A few thoughts:
 >  >=20
 >  >=20
 >  > 1. I agree with the sentiment that this syntactic sugar doesn't
 >  > actually save any verbosity, so it's not really syntactic sugar at
 >  > all.
 >  >=20
 >  >=20
 >  > 2. There appears to now be another RFC by Pavel Patapau, specifically
 >  > focused on a Guard statement as a new keyword
 >  > (https://wiki.php.net/rfc/guard_statement), which now has its separat=
e
 >  > discussion.
 >  >=20
 >  >=20
 >  > 3. As Thomas Lamy mentioned, I too would prefer a single keyword.
 >  > Consider the following two examples:
 >  >=20
 >  >     function foo($bar)
 >  >     {
 >  >         if ($bar =3D=3D=3D 1)
 >  >             return;
 >  >=20
 >  >         if ($bar =3D=3D=3D 666)
 >  >             delete_everything();
 >  >     }
 >  >=20


 >  >=20
 >  > Both would now be valid syntax, and IDEs would have a harder time
 >  > warning about the misplaced semicolon in the second example.  Wouldn'=
t
 >  > be very common, but still.
 >  >=20
 >  >=20
 >  > 4. However, this RFC is interesting to me because there be a way to
 >  > modify it to allow for less verbose refactoring, and kinda allowing
 >  > returns to bubble up like exceptions do.  I think it would only make
 >  > sense if it's a "if not null then return" type of thing.
 >  >=20
 >  > Consider the following (a bit contrived, but I hope you get the point=
):
 >  >=20
 >  >     function main_function()
 >  >     {
 >  >         $result =3D calculate($var);
 >  >         if ($result !=3D=3D null)
 >  >             return $result;
 >  >=20
 >  >         /* do other important stuff */
 >  >     }
 >  >=20
 >  >     function main_function()
 >  >     {
 >  >         ifnotnullreturn calculate($var);
 >  >=20
 >  >         /* do other important stuff */
 >  >     }
 >  >=20
 >  > Obviously not an ideal keyword, but this is the only thing I can thin=
k
 >  > of where this type of syntactic sugar makes sense and decreases
 >  > verbosity.  Something similar can also be accomplished with exception
 >  > though.
 >  >=20
 >  >=20
 >  > 5. Finally, I think if we start putting several returns at the same
 >  > indentation then the cognitive load increases because we can no longe=
r
 >  > tell if a return is actually a return at a glance.
 >  >=20
 >  >=20
 >  > Thanks,
 >  > Peter
 >  >=20
 >=20
 > I agree.=20
 >=20
 > =C2=BF Maybe something like...
 >=20
 >    function main_function()
 >      {
 >          escape when(  calculate($var) );
 >=20
 >          /* do other important stuff */
 >     }
 >=20
 >=20
 > `escape when( expr )`  returns value of  `expr`  to caller function  whe=
n `expr` evaluate to true otherwise next line.
 >=20
 >    function main_function()
 >      {
 >          escape with $ a + 1  when(  !calculate($var)  );
 >=20
 >          /* do other important stuff */
 >     }
 >=20
 >=20
 > `escape with expr1 when( expr2 )`  returns value of `expr1` to caller fu=
nction  when `expr2` evaluate to true otherwise next line.
 >=20
 >=20

Upgrade version.

Maybe is better:

`escape when( expr )`  returns null  to caller function  when `expr` evalua=
te to true otherwise next line.

 `escape with expr1 when( expr2 )`  returns value of `expr1` to caller func=
tion  when `expr2` evaluate to true otherwise next line.

Then these code are equals to:

 >  >     function main_function()
 >  >     {
 >  >         $result =3D calculate($var);
 >  >         if ($result !=3D=3D null)
 >  >             return $result;
 >  >=20
 >  >         /* do other important stuff */
 >  >     }
 >  >=20

function main_function()=20
{
   escape with $result when(   $result =3D calculate($var) );

  /* do other important stuff */
}


 >  >     function foo($bar)
 >  >     {
 >  >         if ($bar =3D=3D=3D 1)
 >  >             return;
 >  >=20
 >  >         if ($bar =3D=3D=3D 666)
 >  >             delete_everything();
 >  >     }


function foo($var) {
  escape when( $bar =3D=3D=3D 1 ||  $bar !=3D=3D 600 );

  delete_everything();
}