TemplateHandler API revision

A few things have already changed.

* TemplateHandler#cache_fragment has been remove. Ensure your template
handler sets a @output_buffer if you want the cache helper to work.
aca246a
* I had to change the method signature for TemplateHandler#render to
take a local_assigns argument since template.locals is no longer
available. 6ebdd0e
* TemplateHandler is initialized with view set to nil when it is
compiling. "ERBHandler.new(nil).compile(template)"

I'd really like deprecate the TemplateHandler#render all together. If
you think your handler can not be compiled, you always just compile in
a delegate call to your "noncompilable" handler. This leaves us with
only one method, compile.

The current state is pretty hacky to attempt to preserve some kind of
"compatibility". It be nice to scrap the current setup and try
something fresh that would fit in better.

A proposed API

  Template.register_extension :erb, lambda { |template|
ERB.new(template.source).src }

Any other ideas? Also, what problems have you had to deal with the
previous implementation?

Checking in from the Haml camp :-).

In general, I'm most happy when nothing changes. Haml has to support
each version of Rails, so the more changes are made the more nasty the
code gets. From a development perspective, the API as of 2.1.0 was
fine; anything divergent from that is just annoying.

A few things have already changed.

* TemplateHandler#cache_fragment has been remove. Ensure your template
handler sets a @output_buffer if you want the cache helper to work.
aca246a

Haml doesn't set @output_buffer, but it does override the
output_buffer and set_output_buffer helpers (specifically because we
don't want to have to figure out when to set @output_buffer). If
cache_fragment uses those, it should work fine.

It won't be a problem if Haml's TemplateHandler subclass still defines
#cache_fragment, will it?

* I had to change the method signature for TemplateHandler#render to
take a local_assigns argument since template.locals is no longer
available. 6ebdd0e

Sure, Haml doesn't override #render anyway.

* TemplateHandler is initialized with view set to nil when it is
compiling. "ERBHandler.new(nil).compile(template)"

Nor does it override the constructor.

I'd really like deprecate the TemplateHandler#render all together. If
you think your handler can not be compiled, you always just compile in
a delegate call to your "noncompilable" handler. This leaves us with
only one method, compile.

Sounds good to me.

The current state is pretty hacky to attempt to preserve some kind of
"compatibility". It be nice to scrap the current setup and try
something fresh that would fit in better.

A proposed API

Template.register_extension :erb, lambda { |template|
ERB.new(template.source).src }

As I mentioned above, I really like compatibility. The proposed API
isn't so bad, since I can just call compile on the TemplateHandler
subclass I've got lying around, but I'd prefer to have
register_template_handler keep working.

Any other ideas? Also, what problems have you had to deal with the
previous implementation?

Again, the main problem is incompatibility. Every time compatibility
breaks, we need to roll out a new version, so if someone updates their
Rails version they need to update Haml as well. We end up with support
requests and users end up with broken apps... it's just no fun all
around.

Haml doesn't set @output_buffer, but it does override the
output_buffer and set_output_buffer helpers (specifically because we
don't want to have to figure out when to set @output_buffer). If
cache_fragment uses those, it should work fine.

If you overriding output_buffer, that will have the same effect.

As I mentioned above, I really like compatibility. The proposed API
isn't so bad, since I can just call compile on the TemplateHandler
subclass I've got lying around, but I'd prefer to have
register_template_handler keep working.

I totally understand. I may make some of those other minor
adjustments, but I'll be sure to leave the TemplateHandler#compile
intact so you don't have to change anything :wink:

Okay, cool, that sounds good.