Document limitations when using lazy loaded dependencies that involve variadic functions

[holtkamp]

When using lazy loaded dependencies, I encountered some curious behaviour when handing over more parameters to a function than defined in its signature (variadic functions).

class Service
{
    /**
     * @param mixed $param1
     * @param mixed $param2
     * @param mixed $paramN Can be used to supply additional parameters
     */
    public function doStuf($param1, $param2){
        echo func_num_args();
    }
}

Now let's try to use this Service when fetched from the dependency injection container

$dic->get('Service')->doStuff(1, 2, 3); //Prints '3' when not lazy loaded
$dic->get('Service')->doStuff(1, 2, 3); //Prints '2' when lazy loaded

I use this approach to inject extra variables when translating messages like: "User X has logged in on Y", where X and Y would be 'additional' parameters.

This probably has to do with the intermediate proxy classes that are generated. For example from a generated proxy class:

  /**
     * {@inheritDoc}
     */
    public function doStuf($param1, $param2)
    {
        $this->initializer5683c4a86687a054344119 && $this->initializer5683c4a86687a054344119->__invoke($this->valueHolder5683c4a866860700867865, $this, 'fireEventOnOrder', array('param1' => $param1, 'param2' => $param2), $this->initializer5683c4a86687a054344119);

        return $this->valueHolder5683c4a866860700867865->fireEventOnOrder($param1, $param2);
    }

When looking at Ocramius/ProxyManager#177, I think this behaviour is expected. Therefore I think it should be mentioned in the documentation as a warning...

[mnapoli]

Well thank you for going so far in the debugging :)

Ping @Ocramius. It seems Ocramius/ProxyManager#177 is about supporting PHP 5.6's variadics (the ... syntax), so I'm guessing it might simply be a bug in ProxyManager? (i.e. it should use func_get_args() instead of listing each parameter?)

[Ocramius]

@mnapoli I still need to pack variadics, scalar type hints and return type hints into ProxyManager.

[mnapoli]

Just to be sure, when you say variadics you also mean "PHP < 5.6 kind of variadics" which consists of passing more parameters than defined right?

In that case indeed we could document in PHP-DI that this is not supported right now to avoid confusion.

[Ocramius]

Just to be sure, when you say variadics you also mean "PHP < 5.6 kind of variadics" which consists of passing more parameters than defined right?

No, I mean 5.6 variadics (... operator).

Pre-PHP-5.6 "variadic arguments" are totally ignored. Going to open an issue for that now.

[Ocramius]

Note: this is also broken in doctrine2, now that I notice it (known, but undocumented limitation).

Actually, the lazy loading ghost objects in ProxyManager 2.x work with that one, but I still need to implement them.

Opened Ocramius/ProxyManager#265 to track that, thanks!

[mnapoli]

Thanks!

[Ocramius]

I provided documentation for this sort of problem in ProxyManager and fixed the support of variadic arguments in the 2.x branch.

There is also a possible resolution path for this particular issue at Ocramius/ProxyManager#269, but it is complex and for a super-edge case.

I'll get a 2.0 release out soon, but be aware that:

• it will work with PHP "~5.6|~7.0"
• there will be some BC breaks

[mnapoli]

👍 I was just reading this ;) Thanks

[holtkamp]

just checking on the status on this to see whether this issue can be closed...

ProxyManager 2.0 have been released for a while now and Ocramius/ProxyManager#265 is closed. But I am not sure whether the named 'Ghost objects' which should support the pre-PHP-5.6 variadic functions is already implemented.

[mnapoli]

But it seems that v2 requires PHP 7 right?

[holtkamp]

aah, yeah seems to be the case: https://github.com/Ocramius/ProxyManager/blob/6c89b7bd6039d8047b1473e2074cb56baa4bc15d/composer.json#L22

Can we then conclude this will not be resolved for the time being and this limitation needs to be documented?

[mnapoli]

Yep!

[Ocramius]

Note: you can require ~1.0|~2.0, since the API didn't change massively. Please see symfony/symfony#17919 for a reference implementation of a BC compliant way of doing this.

As for the rest: you simply need to document that lazy services with variadic signatures require PHP 7 and the latest ProxyManager.

[mnapoli]

👍 good idea! Thanks for the links

[holtkamp]

Aah, nice approach 😉

[holtkamp]

@mnapoli are you considering adopting the suggestion of @Ocramius ? Guess it would be similar to: https://github.com/doctrine/migrations/blob/5f9429e5e6dd31d0f36c8951daa184112a39e195/composer.json#L18

[mnapoli]

Oh yes I'm definitely up for it, I just didn't have time to implement it yet. I guess what's to do:

• update ProxyFactory if necessary to make it compatible with both version (since it's very simple it's possible there is nothing to do)
• require ~1.0|~2.0, tests should run with highest and lowest version on Travis automatically
• update the documentation

If you are up for it I'll be 👍 to merge it!

[mnapoli]

Fixed in #414 (PHP-DI can now be installed with ProxyManager ~1.0 or ~2.0).

[Ocramius]

@mnapoli awesome! I really hope to push those 2.0 installations up (too many 1.x users ;-) )