Question

I was wondering if it was possible to determine what the current namespace was when the function was being called. I have this function declaration:

<?php
namespace Site\Action;
function add ($hook, $function) {
    /**
     * determine the namespace this was called from because
     * __NAMESPACE__ is "site\action" :(
     */
     if (is_callable($function))
         call_user_func($function);
}
?>

And on another file:

<?php
namespace Foo;
function bar () {
}
?>

And let’s say I have this as my procedural code:

<?php
namespace Foo;
Site\Action\add('hookname', 'bar');
?>

It would make sense to assume that Bar in this case was intended to resolve as Foo\bar since that was the namespace it was called from.

That was a long explanation so again, is it possible to determine the active namespace where Site\Action\add() was called from?

Thanks in advance.

Answer 1

What you are looking for is : ReflectionFunctionAbstract::getNamespaceName

If you want to know where you’re coming from debug_backtrace() is your friend.

The following should solve your puzzle:

function backtrace_namespace() 
{
    $trace = array();
    $functions = array_map(
        function ($v) {
            return $v['function'];
        },
        debug_backtrace()
    );
    foreach ($functions as $func) {
        $f = new ReflectionFunction($func);
        $trace[] = array(
            'function' => $func, 
            'namespace' =>  $f->getNamespaceName()
        );
    }
    return $trace;
}

Just call it from anywhere to see the backtrace.
I modified your “procedural” code file as follows:

namespace Foo;

function bar () 
{
    var_export(backtrace_namespace());
}

/** The unasked question: We need to use the fully qualified name currently. */
function go() 
{
    \Site\Action\add('hookname', 'Foo\\bar');
}

go();

The Result from including this file will be the following on stdout:

array (
    0 =>
    array (
        'function' => 'backtrace_namespace',
        'namespace' => '',
    ),
    1 =>
    array (
        'function' => 'Foo\\bar',
        'namespace' => 'Foo',
    ),
    2 =>
    array (
        'function' => 'call_user_func',
        'namespace' => '',
    ),
    3 =>
    array (
        'function' => 'Site\\Action\\add',
        'namespace' => 'Site\\Action',
    ),
    4 =>
    array (
        'function' => 'Foo\\go',
        'namespace' => 'Foo',
    ),
)

Now for bonus points the answer to the hidden question:

How do I resolve the calling namespace to avoid using fully qualified function name as argument?

The following will allow you to call the function as you intended:

 Site\Action\add('hookname', 'bar');

Without getting the dreaded:

Warning: call_user_func() expects parameter 1 to be a valid callback, function ‘bar’ not found or invalid function name

So before you redesign try this on for size:

namespace Site\Action;

function add($hook, $function) 
{
    $trace = backtrace_namespace();
    $prev = (object) end($trace);

    $function = "$prev->namespace\\$function";

    if (is_callable($function))
        call_user_func($function);
}

I see no reason why debug_backtrace should not be used, this is what it is there for.

nJoy!