[Workfow] Management of expressions in guard Listerner (and all others components)

[lyrixx]

Q	A
Bug report?	no
Feature request?	no
BC Break report?	no
RFC?	yes
Symfony version	all

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Hello.

In different places place of Symfony, we can configure things with an expression. Some exemples:

• In the security component (and related): https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Security/Core/Authorization/ExpressionLanguageProvider.php and https://github.com/sensiolabs/SensioFrameworkExtraBundle/blob/master/EventListener/SecurityListener.php
• To Block a transition in the Workflow: https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Workflow/EventListener/ExpressionLanguage.php
• And some other parts of the framworks

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Yesterday I was working on #23499 and #23906 And I think we have an issue with the current implementation of the expression in the workflow component (and also with other component).

With theses 2 PR if someone wants to use only is_valid and if the security is not enable of if the user is not connected he will get an exception: https://github.com/symfony/symfony/pull/23906/files#diff-7e071774bef81a2a6e1b4e5d81d8ace8R59 ; That's not cool.

I guess we can fix this by moving this check right here

But still, I'm not really happy with that.

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The EL has two modes: a runtime and a compiled mode. But now I fail to see how someone could use the compiled mode with the current implementation (in the workflow, but also with the @Security annotation).

So, we do have checks for the runtime mode but not for the compiled mode (just above). So here it can lead to a fatal error.

So if it's not possible at all to use the compiled in theses uses case, why don't we use propose injection in classes like https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Workflow/EventListener/ExpressionLanguage.php or https://github.com/sensiolabs/SensioFrameworkExtraBundle/blob/master/Security/ExpressionLanguage.php insteand of relying of the presence or not of a special var? Obviously That would made the compiled mode unable to work.

Note: I did not check for the integration between the EL and the Router or the DIC. But I guess thing are optimized there (or it could be)

Note2: In Blackfire there are place where you can configure some expression and when I implemented this feature I did not used the pattern used in Symfony. I disabled the compiled mode and I used propre inject in the ExpressionLanguage class (or FunctionProvider, it's the same things). It was really simpler and flexible.

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I would like to use propre injection in the workflow component, and if it's applicable also in other component.

What do you think ?

[Simperfit]

I agree, I think it could be great to have this in the workflow component. Do you still want to implement it ?

[lyrixx]

Sure.

[lyrixx]

If no one is against it, I will implement it this week.

[lyrixx]

Actually, this is complicated to implement it. Let's close this issue as it's not so important