Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:114546
To: internals@lists.php.net
References: <CAF+90c_iYjsDWoqPaDtavVgj2WFdpiuBmGeQZFAqokVoVZTxoA@mail.gmail.com>
 <CAAwdEzC7ELqrGE0PMZ7ParYEN0CrHNVP1rnSvwW=Smcvdp41-Q@mail.gmail.com>
Message-ID: <1a024ec2-60c0-4a48-5f1e-4a4369a6a642@gmail.com>
Date: Thu, 20 May 2021 20:54:16 +0100
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.10.1
MIME-Version: 1.0
In-Reply-To: <CAAwdEzC7ELqrGE0PMZ7ParYEN0CrHNVP1rnSvwW=Smcvdp41-Q@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-GB
Subject: Re: [PHP-DEV] [RFC] First-class callable syntax
From: rowan.collins@gmail.com (Rowan Tommins)

On 20/05/2021 19:16, Alexandru Pătrănescu wrote:
> Also, considering the resolution between property and method (or between
> constants and static methods) , it's clear that we need a syntax that looks
> like the usual invocation:(...), or (?), (...?), ($), ($$), (...$) etc.


I'd like to expand on this point, because I'm seeing a lot of 
suggestions for syntaxes that overlook it.

The following are all valid, but refer to _different_ things called "foo":

foo // a constant called foo
foo() // a function called foo
$foo // a variable called foo

$bar->foo // a property called foo
$bar->foo() // a method called foo

Bar::foo // a class constant
Bar::foo() // a static method
Bar::$foo // a static property

The thing that consistently distinguishes function and method calls is 
the parentheses after them. This holds even for "exotic" combinations:

$foo() // a variable called foo, de-referenced as a callable and then 
invoked
($bar->foo)() // a property called foo, de-referenced as a callable and 
then invoked
foo()() // a function called foo, the return value of which is 
de-referenced as a callable and invoked

Any callable syntax (and, if/when we get one, a partial application 
syntax) that doesn't have the parentheses there is going to run into 
annoying edge cases fast. Not necessarily the kind of edge cases that 
are hard for the parser, but definitely the kind that are confusing to 
humans.


Regards,

-- 
Rowan Tommins
[IMSoP]