native php `is_true` and `is_false`?

[kocoten1992]

Description

Hi maintainer,

PHP have is_null, It feel a bit inconsistent when typing $x === false, could PHP have is_false and is_true as well?

[damianwadley]

I'm going to step up and say no: PHP doesn't need to add more top-level functions with trivial implementations.

is_null dates back to the days when PHP didn't have things like closures or arrow functions, and when callback arguments were strings of function names. Having a built-in function for a common use case like checking for null values made sense back then because you could pass "is_null" to functions like array_filter. But nowadays, if you want to check if a value is literally null - or true or false, or 0 or an empty string or any other value for that matter - then it's plenty easy to use === in every situation.

[damianwadley]

...that said, there is one potential benefit: making is_true/is_false a typecheck opcode like is_null. It still "requires" creating the functions for real though, which is the least appealing aspect to me. Plus, then what about "is_zero" or "is_empty_string" or "is_empty_array" or a whole bunch of other possible is_* functions? Perhaps keeping that door closed would be for the best.

[kocoten1992]

Hi @damianwadley, it more of language consistency than just an implementation (when null/true/false is now a standalone type).

[damianwadley]

true and false are not types.

But what consistency are you talking about? Type hints? is_resource exists but you cannot use "resource" as a type. is_double exists but you cannot use "double" as a type. Same for is_countable and is_integer and is_long and is_numeric and is_scalar. In the other direction, for obvious reasons there is no is_mixed function.

And, if you didn't notice, while null and false are allowed as of PHP 8.2, true was deliberately excluded, so that's already inconsistent.

[kocoten1992]

Hi, the consistency is just my feeling when developing app, as most php function like to return a type with false, like:
file_get_contents, fopen, curl_exec...

I also use laravel web framework, it have an database abstraction layer called eloquent, when using it, it does thing differently (when call to database fail it will not return false, but rather throw exception), when query no result, it will return null, I use is_null to deliberating checking (and not using type casting like: if (! $result), because phpstan or psalm will complain about type).

When I use back built in php function, I got familiar with how checking for primitive type with built in function like is_null and not using ===, that the inconsistent (as least it how I feel when writing modern php with phpstan support).

In the end, it just a feeling. I have no complain.

[cmb69]

I agree with @damianwadley; I don't see the need for these functions either. Although true can be used as type as of PHP 8.2.0 as well, a strict comparison with the single value of these types works just fine, and I don't think that we would add is_null() nowadays.