[TwigBundle] Make twig extension handle custom template escaping guesser

[maxbeutel]

I wanted to add a custom template escaping guesser for twig like in http://twig.sensiolabs.org/doc/recipes.html#using-the-template-name-to-set-the-default-escaping-strategy

This pull request allows you register a service id and a method as a custom guesser:

twig:
    autoescape: my_service:guess

Documentation is missing for this PR and the unit tests are not that good. I´d work on it if this PR has any chance of getting merged?

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	none
License	MIT
Doc PR	(missing)

[lstrojny]

👏

[fabpot]

Looks like a good addition to me.

I would use a notation that would respect how we reference services elsewhere:

twig:
    autoescape_service: @my_service
    autoescape_service_method: guess

Also, beside documentation, you should add a note in the component CHANGELOG describing the new feature.

[maxbeutel]

I added the new config settings.

[maxbeutel]

Added documentation, see above

[stof]

@fabpot I would remove the @.

• @ has no special meaning in the semantic config
• @ is not used in XML
• we would need to strip it before using
• we don't use the @ in existing places allowing to configure a service id (in SecurityBundle for instance)

[maxbeutel]

ping @fabpot any desicion on this? Currently its implemented that the @ is stripped.

Also another question: Is there any chance of getting this PR also backported to 2.1. or 2.2. ?

[canni]

@maxbeutel no, there is no chance for this to be backported, only bug-fixes can be applied to older branches

IMO we could consider to structure this similarly to what we have (ie form fields type guessers) It would be great that guessers can be classes that implement common interface and are registered as a tagged services, and passed to something like a chained guesser, then each bundle will be able to easily define its own guessers (with possibly its own escaping rules) - for now this can be little overhead, but will save us enough playground and flexibility for future

[lstrojny]

@canni this sounds way too complicated for such a simple task.

[stof]

@canni Twig expects a callable. The goal here is simply to define a callable as array($service, $method)

[lstrojny]

What about the @? Can we reach a final decision here and go on?

[fabpot]

Let's remove the @ altogether.

@maxbeutel After removing the @, can you submit a PR on the documentation so that I can merge?

[fabpot]

I've made the needed changes and changed the XSD to use - instead of _ as a word separator.

@maxbeutel Can you submit a PR on the documentation? Thanks.

[maxbeutel]

@fabpot I added docs here symfony/symfony-docs#2459 thanks for merging and doing the changes!