How to call methods from extended classes with different namespaces in PHP

Question

The question was made because I had an error in finding the actual namespace in the situation:

parent class namespace \demo\parent\config() (hundreds of lines)
child class namespace \demo\child1\config() extends \demo\parent\config() (empty)
child class namespace \demo\child2\config() extends \demo\parent\config() (empty)

But... I uncovered it was not a problem with this but I did a) not fully quantify my class_exists() (assuming the class would take the namespace above it but it does not) AND I had a type in my class_exists line...

Anyway this workaround works for getting the actual namespace:

workaround

If I use something getnamespace:

function getNameSpace()
{
    $currentClass = get_class($this);
    $refl = new \ReflectionClass($currentClass);
    $namespace = $refl->getNamespaceName();
    return $namespace . '\\';
}

and then something like the following for instantiating the class in its correct namespace

$module1 = '\\' . self::getNameSpace() . 'Module1';
new $module1

and in the scenario of static classes:

self::callConfig('GetOptionsName');

where "callConfig" =

function callConfig($method,$par='')
    {
        if ('' == $par)
        {
            return call_user_func(array(self::getNameSpace() . 'Config',
                $method));
        }
        else
        {
            return call_user_func_array(array(self::getNameSpace() . 'Config',
                $method),$par);
        }
    }

'Config' from the current namespace of a file should get precedence, so this should just work. Can you show an example of the situation where this fails? — Evert
– Evert, Commented Feb 5, 2012 at 20:59
Or is the true problem here that you try to call all your methods statically, while you should really just create an instance of an object? — Evert
– Evert, Commented Feb 5, 2012 at 21:00
a) 'Config' of the current namespace of a file gets precedence, but I would like to have the child namespace (the one that extends the abstract class) — edelwater
– edelwater, Commented Feb 5, 2012 at 21:09
b) probably refactoring Config to an instantiation instead of a central static class would be better but... in this case means refactoring dozens of files searching for hundreds of calls to "Config" AND making sure the instantiated config object is used in all of these files. — edelwater
– edelwater, Commented Feb 5, 2012 at 21:12

Evert · Accepted Answer · 2012-02-06 10:24:36Z

1

So the real answer here is that you made a design mistake. Too big to refactor (although in reality, it may not be that bad). So to work around your design mistake, you need to hack thing together like you are right now.

There's an extremely good reason why there's a difference between a class and object. Objects allow for subclassing, and all those fancy OOP features are tied to classes being instantiated. My guess is you picked aesthetics over usefulness.

Perhaps you can make the problem not as big, if you consider Config:: more or less as a proxy to your real configuration. I would still want to suggest to rewrite this bit of your codebase to properly leverage OOP, and then perhaps use your existing Config:: for backwards compatibility. If your application is supposed to live a long time, you may feel that introducing a new concept (and maintaining the old one) may be worthwhile in the long run. Otherwise you may have to live with this bad decision a long, long time.

Lastly, give refactoring a shot. I found even with massive codebases, it may be a boring job.. but nothing that will take more than a few hours.

If you had unittests, it would have also been very easy to verify that this change is correctly implemented everywhere.

answered Feb 6, 2012 at 10:24

Evert

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5 Comments

edelwater Over a year ago

a. yes i could rewrite everything but b. what is the php way to do this? it wont work with getnamespace or with get_class since that will return multiple names if you have multiple child classes in multiple namespaces

Evert Over a year ago

You will not find a nice, well working PHP-way because you are abusing how PHP is supposed to work. Namespace are intended to be a parse & author-time only convenience, and namespaces making their way into the run-time phase is a 'bad thing'.

edelwater Over a year ago

so you say that this : php.net/manual/en/language.namespaces.rules.php step 5 and 6 are bad practice of PHP because they take into account run-time processing of namespaces ? (or should have a warning sign added) ?

edelwater Over a year ago

Actually... I found out that it works simply by the code above. My mistake was that I did not fully quanitfy the namespaces in the "class_exist" I assumed they would use the current namespace but they do not. After that ... it clicks together. I don't know exactly about your strong arguments about using namespaces during run-time is a bad thing. Im not using it "run-time" as in "doing weird stuff" I'm simply asking during run-time which namespace is actually used. So maybe you mean "using reflection to base actions on during run-time is a bad thing?"

Evert Over a year ago

@edelwater, to respond to your point about step 5 & 6 from that page. No, nothing bad about depending on that behaviour. I would think it's bad that if you call function A() from a specific file, but function A() might mean a global function, or a local function depending on a run-time condition.

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