GemPlugin install scripts

I'm writing a rails plugin, and figured I'd do it as a GemPlugin to be
ahead of the curve. I need to install some assets when the plugin is
installed in a rails app, but it would seem there's no mechanism by
which this occurs; install.rb is never run for a GemPlugin, unless I'm
missing something entirely.

I could check for the assets in init.rb and copy them over if they
don't exist, but that strikes me as poor behavior. I would guess the
thing to do would be to create a new gems task, gems:plugin:install or
similar, which would invoke the install scripts on all config.gems
that have been tagged with :plugin => true. Before I dive in and give
this a whirl, though, I figured I'd check with the dev team and see if
a. I've overlooked an existing installation mechanism, b. someone
already had something in the works, or even c. the GemPlugin idea was
still considered to be the future of plugins, or if yet another
strategy was being considered.

- donald

I agree that there should be an install hook. Gem plugins are just plugins that have the benefits of rubygems.

But it’s not easy. Plugins had an interface for installing: “script/plugin install”. Gems, on the other hand, can be installed in a variety of ways: from referencing them in environment.rb to freezing them in the application.

But now, less and less people use “script/plugin” in favor of dependencies management tools. Same could be used for “freezing” gems (see recent discussions on this list).

http://github.com/gary/dependency_management_talk/tree/master/notes.markdown

This poses a question: how to trigger an install hook when you don’t control the means of installation anymore? Maybe the 3rd party tools should follow the standard to execute install.rb when they see it. But how will they provide the same environment Rails did when it executes them in “script/plugin”?

Another question is are installation hooks worth this trouble? All they do is show README on the console or copy assets to “public/”. The former is just luxury, while the latter can easly be available through rake/thor tasks.

I would guess the
thing to do would be to create a new gems task, gems:plugin:install or
similar, which would invoke the install scripts on all config.gems
that have been tagged with :plugin => true.

I agree that there should be an install hook. Gem plugins are just plugins
that have the benefits of rubygems.
But it's not easy. Plugins had an interface for installing: "script/plugin
install". Gems, on the other hand, can be installed in a variety of ways:
from referencing them in environment.rb to freezing them in the application.
But now, less and less people use "script/plugin" in favor of dependencies
management tools. Same could be used for "freezing" gems (see recent
discussions on this list).
http://github.com/gary/dependency_management_talk/tree/master/notes.markdown

Regardless of how the gems are actually installed, folks are still
"supposed" to use config.gems to require all the gems used by their
rails apps, right? If so, couldn't you still tag those gems that are
also plugins in the config file and provide a gems:plugins:install
task to run any plugin install scripts?

Another question is are installation hooks worth this trouble? All they do
is show README on the console or copy assets to "public/". The former is
just luxury, while the latter can easly be available through rake/thor
tasks.

I agree the former is unnecessary. Can the latter in fact be done with
rake tasks? That is to say, can system gems make rake tasks globally
available? Or are you proposing some mechanism by which gems required
via config.gem can be queried for rake tasks they make available to
the rails app?

- donald

I clearly wasn’t thinking at all when I said that. But now that you mention it, theoretically it’s possible for gem plugins referenced in environment.rb to expose some sort of tasks. Most of the rails rake tasks load the environment, anyway …