Using function prototypes dynamically in PHP
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10-07-2019 - |
Question
I'm writing a construct in PHP where a parser determins which function to call dynamically, kind of like this:
// The definition of what to call
$function_call_spec = array( "prototype" => "myFunction",
"parameters" => array( "first_par" => "Hello",
"second_par" => "World"));
// Dispatch
$funcPrototype = $function_call_spec["prototype"];
$funcPrototype(); // Here we call function 'myFunction'.
This is all fine and dandy. But now comes the next step, passing the parameters, which I don't really know if it's possible the way I want to do it. It never stops amazing me however what script languages can do these days, so here goes:
One could pass the parameters to the function like this:
// Here we call function 'myFunction' with the array of parameters.
$funcPrototype( $function_call_spec["parameters"] );
However, I want to declare 'myFunction' properly with clear arguments etc:
function myFunction( $first_par, $second_par )
{
}
The question then follows - Is there any way to pass parameters to a function dynamically simply by looping through the parameter array?
To clarify, I don't want to do it like this:
$funcPrototype( $function_call_spec["parameters"]["first_par"],
$function_call_spec["parameters"]["second_par"] );
Because this requires my code to statically know details about myFunction, which goes against the whole idea.
Instead I would want to do it in some way like this maybe:
// Special magic PHP function which can be used for invoking functions dynamically
InvokeFunction( $funcPrototype, $function_call_spec["parameters"] );
Which then results in myFunction being called and all parameters in the array gets passed to each individual parameter variable in the prototype.
Any comments are welcome.
Regards.
/R
PS: None of the code in this post has been tested for typos etc.
Solution
You should use call_user_func_array
which can call any function or method and takes parameteres from an array.
Alternatively you can use ReflectionFunction::invokeArgs
, but there's no benefit over call_user_func_array
unless you already use this class for someting else (like checking whether function you call accepts appropriate number and types of arguments).
OTHER TIPS
call_user_func_array($funcPrototype, $function_call_spec["parameters"]);
You might want to create a wrapper that names the function to your preference, such as:
function InvokeFunction($function, $args = array()) {
return call_user_func_array($function, (array)$args);
}
With this function you can call it in 3 different ways:
$return = InvokeFunction('doStuff');
$return = InvokeFunction('doStuff', $single_arg);
$return = InvokeFunction('doStuff', $multiple_args);
call_user_func_array()
is the best choice if you don't need to enforce the contract, otherwise use ReflectionFunction
.
http://us2.php.net/create_function
When you use create_function(), your arguments are not evaluated until runtime. Pretty sweet.