Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:98461
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 74.125.82.51 as permitted sender)
To: internals@lists.php.net
References: <CAPhkiZzs=kLF-JKBjX4bVgADz+nonERWuZYiYo8cXA=GrXKU=g@mail.gmail.com>
 <b5b31f6e-2e43-b37d-33b6-5cd2bcd809ba@gmail.com>
 <3b1ab2d7-c572-14a7-da37-d5b7e379326e@fleshgrinder.com>
Message-ID: <6ccec0fb-a2b7-8421-87d3-46bd0fa4ddc4@gmail.com>
Date: Thu, 9 Mar 2017 19:51:23 +0000
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101
 Thunderbird/45.8.0
MIME-Version: 1.0
In-Reply-To: <3b1ab2d7-c572-14a7-da37-d5b7e379326e@fleshgrinder.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] [Discussion] is_string(), string type and objects
 implementing __toString()
From: rowan.collins@gmail.com (Rowan Collins)

On 09/03/2017 17:37, Fleshgrinder wrote:
> On 3/9/2017 3:18 AM, Stanislav Malyshev wrote:
>
>> I don't think it's right approach. is_* functions check the current type
>> of the value, not whether it can be converted to another type. If we
>> need ones that express the latter, we should have different functions.
>>
>> Also, as already noted, having __toString doesn't mean it returns
>> something useful.
>>
> This is not true at all:
>
> 1. is_dir
> 2. is_executable
> 3. is_file
> 4. is_finite
> 5. is_infinite
> 6. is_link
> 7. is_nan
> 8. is_readable
> 9. is_resource (checks the resource's type too)
> 10. is_uploaded_file
> 11. is_writable

I think a good example is "is_callable", which evaluates not the *type* 
of the value, but the *possible behaviour*. You could think of 
Closure::fromCallable($foo) as "cast $foo to Closure", in which case 
is_callable($foo) is "can $foo be cast to Closure?" (at least, in it's 
default behaviour).

This is then much more similar to defining is_stringable($foo) to return 
true for everything that can be cast to string.

Regards,

-- 
Rowan Collins
[IMSoP]