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Bug #76054 is_a does not accept scalar types
Submitted: 2018-03-05 18:27 UTC Modified: -
Votes:1
Avg. Score:2.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:1 (100.0%)
Same OS:1 (100.0%)
From: tom at r dot je Assigned:
Status: Open Package: Reflection related
PHP Version: 7.2.3 OS: any
Private report: No CVE-ID: None
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 [2018-03-05 18:27 UTC] tom at r dot je
Description:
------------
I cannot easily work out whether a function can be successfully called with a given set of values if there are scalar type hints. 

Ideally I'd like to do this:


<?php
function foo(string $a, callable $bar) {

}


//I want to check to see whether these arguments can be used to call the function
$arguments = [123, 'not-callable!'];

//Or these valid arguments
// $arguments = ['A string', function() {}]; //This should pass the check

// To do this, I need to check to see whether the arguments match the type hint

$reflect = new ReflectionFunction('foo');

$valid = true;
foreach ($reflect->getParameters() as $i => $param) {
	if ($param->getType()) {
		//check to see if the type $arguments[$i] matches the type hint
		//e.g. would evaluate to is_a('string', 123);
		if (!is_a($param->getType()->getName(), $arguments[$i])) $valid = false;

	}
}


echo $valid ? 'Function foo can be called with supplied $arguments' : '$arguments do not match function definition.';

?>


However, because is_a does not allow scalar types in the first argument, it's not possible. Instead, I need to do this:


<?php

function foo(string $a, callable $bar) {

}


//I want to check to see whether these arguments can be used to call the function
$arguments = [123, 'not-callable!'];

//Or these valid arguments
// $arguments = ['A string', function() {}]; //This should pass the check

// To do this, I need to check to see whether the arguments match the type hint

$reflect = new ReflectionFunction('foo');

$valid = true;
foreach ($reflect->getParameters() as $i => $param) {
	if ($param->getType()) {
		$type = $param->getType()->getName();
		if ($type == 'string' && !is_string($arguments[$i])) $valid = false;
		else if ($type == 'int' && !is_int($arguments[$i])) $valid = false;
		else if ($type == 'callable' && !is_callable($arguments[$i])) $valid = false;
		else if ($type == 'array' && !is_array($arguments[$i])) $valid = false;
	}
}


echo $valid ? 'Function foo can be called with supplied $arguments' : '$arguments do not match function definition.';

?>

Or, alternatively, this hacky as hell workaround:


<?php

function foo(string $a, callable $bar) {

}


//I want to check to see whether these arguments can be used to call the function
$arguments = [123, 'not-callable!'];

//Or these valid arguments
// $arguments = ['A string', function() {}]; //This should pass the check

// To do this, I need to check to see whether the arguments match the type hint

$reflect = new ReflectionFunction('foo');

$valid = true;
foreach ($reflect->getParameters() as $i => $param) {
	if ($param->getType()) {
		if (!call_user_func('is_' . $param->getType()->getName(), $arguments[$i])) $valid = false;
	}
}


echo $valid ? 'Function foo can be called with supplied $arguments' : '$arguments do not match function definition.';



?>



Ideally, is_a should support scalar types but perhaps adjusting reflection to allow $param->getType()->willAccept($value); or similar would  work as well because at the moment, to determine this, we need to do two checks: One for $param->getClass() and another for $param->getType()




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