Passing a parameter to a callable function

Question

I can't seem to get this to work. I have a function which takes a parameter which I would like to call.

protected function testFunc($param) {
    echo $param;
}

protected function testCall(callable $testFunc) {
    call_user_func($testFunc);
}

public function testProg($param) {
    $this->testCall([$this, 'testFunc']);
}

I have tried

$this->testCall([[$this, 'testFunc'], $param]);

and

$this->testCall([$this, 'testFunc($param)']);

and

$this->testCall('TestClass::testFunc($param));

Are closures my only option here or how can I pass a parameter to a callable function

Answer 1

To call a method (in your example function(s) are class methods), you have to use this syntax:

protected function testCall( $testFunc )
{
    call_user_func( array( $this, $testFunc ) );
}

To pass an argument, you have to use this syntax:

protected function testCall( $testFunc, $arg )
{
    call_user_func( array( $this, $testFunc ), $arg );
}

(...)

$this->testCall( 'testFunc', $arg );

To pass more than one arguments, you have to use call_user_func_array:

protected function testCall( $testFunc, array $args )
{
    call_user_func_array( array( $this, $testFunc ), $args );
}

(...)

$this->testCall( 'testFunc', array( $arg1, $arg2 ) );

Edit:

The above code works fine, but — as quick-wittedly noted in comments — this previous code:

protected function testCall( callable $testFunc, $arg )

doesn't work in above context.

To use it, the above methods and call must be modified in:

protected function testCall( callable $testFunc, $arg )
{
    call_user_func( $testFunc , $arg );
}

(...)

$this->testCall( array( $this, 'testFunc'), $arg );

Answer 2

Modify your code as follows

protected function testFunc($param) {
    echo $param;
}

protected function testCall(callable $testFunc, $param) {
    call_user_func($testFunc, $param);
}

public function testProg($param) {
    $this->testCall([$this, 'testFunc'], $param);
}

That way, first function (testCall) is accepting arguments for second function (testFunc).

This code works only if you're passing a single argument. If you wish to pass an array, use call_user_func_array