added support for callbacks from gogiel/delayed_paperclip

[filipepina]

added the following callbacks:
post_processing_callback
pre_processing_callback
post_update_callback

requested on issue #176

[slin1202]

Do you know how to add a callback for failure?

[filipepina]

@slin1202 hmmm not sure if paperclip will trigger an exception in that case... maybe checking if the style exists on "post_processing_callback" would solve your problem?
like... object.file.exists?(:style_in_question)

[slin1202]

Ah that might work, thanks!

[martinsabo]

Hi everybody (@filipepina @slin1202 ),
is there any specific reason why this PR is not merged and closed?
It is really useful feature for some usage scenarios. Can I help somehow with this?

Thanks.

[jrgifford]

The reason it hasn’t been merged and closed is because the maintainers are doing this (and many other things) on their nights and weekends. Half of us don’t even have an application that uses delayed_paperclip anymore, so it’s very hard for us to test these scenarios ourselves.

[martinsabo]

@jrgifford ok, understand.

Is there any chance that you merge it when I create another PR with this feature ported to latest version (with specs and updated docs)?

[martinsabo]

@jrgifford nevermind. I have refactored myself out of need of this feature. Yet I need to say that the changes from this PR worked fine. Did not stumbled on any side-effects so far during time I have used it.