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Date: Fri, 15 May 2020 20:58:05 +0200
To: PHP internals <internals@lists.php.net>
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In-Reply-To: <f9109d72-f3d3-5b12-16bb-9ec03d164cf4@ralphschindler.com>
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Subject: Re: [PHP-DEV] Proposal For Return-If / Early Return / Guard
 Clause Syntax
From: crocodile2u@gmail.com (Victor Bolshov)

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Hi internals,

I think it's just as good to write:
if ($condition) return $retval;
Yes, there are subtle semantic differences the new syntax would emphasize, but it doesn't feel like it justifies it. New syntax also means the need to support it, for IDEs and other tools, static analysis tools, code-style tools - and all that for a very tiny benefit, if any.
Cheers,
Victor

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On May 10 2020, at 5:49 pm, Ralph Schindler <ralph@ralphschindler.com> wrote:
> Hi! # Intro I am proposing what is a near completely syntactical addition (only change is to language.y) to the language. The best terminology for this syntax is are: `return if`, "return early", or "guard clauses". see: https://en.wikipedia.org/wiki/Guard_(computer_science) Over the past few years, I've seen a growing number of blog posts, conference talks, and even tooling (for example code complexity scoring), that suggest writing guard clauses is a good practice to utilize. I've also seen it more prevalent in code, and even attempts at achieving this with Exceptions (in an HTTP context) in a framework like Laravel. see abort_if/throw_if: https://laravel.com/docs/7.x/helpers#method-abort-if It is also worth mentioning that Ruby has similar features, and I believe they are heavily utilized: see: https://github.com/rubocop-hq/ruby-style-guide#no-nested-conditionals # Proposal In an effort to make it a first class feature of the language, and to make the control flow / guard clause
s more visible when scanning code, I am proposing this in the syntax of adding `return if`. The chosen syntax is: return if ( if_expr ) [: optional_return_expression] ; As a contrived example: function divide($dividend, $divisor = null) { return if ($divisor === null || $divisor === 0); return $dividend / $divisor; } There is already a little discussion around the choice of order in the above statement, the main take-aways and (my) perceived benefits are: - it keeps the intent nearest the left rail of the code (in normal/common-ish coding standards) - it treats "return if" as a meta-keyword; if must follow return for the statement to be a guard clause. This also allows a person to more easily discern "returns" from "return ifs" more easily since there is not an arbitrary amount of code between them (for example if the return expression were after return but before if). - it has the quality that optional parts are towards the end - is also has the quality that the : return_expression;
 is very symmetrical to the way we demarcate the return type in method signatures "): return type {" for example. - has the quality of promoting single-line conditional returns # Finally One might say this is unnecessary syntactic sugar, which is definitely arguable. But we do have multiple ways of achieving this. Of course all of these things should be discussed, I think sub-votes (should this PR make it that far) could be considered. The PR is located here: https://github.com/php/php-src/pull/5552 As mentioned, some discussion is happening there as well. Thanks! Ralph Schindler PS: since implementing the ::class feature 8 years ago, the addition of the AST abstraction made this kind of syntactical change proof-of-concept so much easier, bravo! -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php


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