Specify Ruby files order through magic comments

[palkan]

Disclaimer

I marked this PR as Experimental to emphasize that it's the main purpose is to discuss the problem (or this is not a problem at all?).

The problem

Currently, Ruby files are loaded and compiled in lexicographical order. Thus we have to use such tricks as using file prefixes just to control this (even in mruby core). And that's an example from my lib (which inspired me to write this).

So, there is no way (other then naming hacks) to specify dependencies (usually we need it when using modules with shared logic).

The Idea

I was thinking of how to tell the builder to compile Ruby files in the specified order and came up with the following idea: let's use magic comments to declare dependencies:

# require: utils/logging

class Base
  include Utils::Logging
  ...
end

Looks like Sprockets 😏

Pros: easy to use/read, backward-compatible.

Cons: that differs from Ruby.

Other ideas

Another option I see is to specify the build order hints somewhere in config:

# Load specified files first, then everything else
conf.compile_first = %w(utils/**/*.rb zzz.rb)

Pros: no language changes.
Cons: harder to maintain (maybe, that's OK for mRuby libs, 'cause they're usually not too big).

[bovi]

I agree that this is an annoying problem. I actually fall several times over this. Yet I don't like the magic comment. The load specific config file on the other side I like.

[christopheraue]

Well, you can already use

conf.rbfiles = Dir["#{conf.dir}/mrblib/utils/**/*.rb"] + Dir["#{conf.dir}/mrblib/zzz.rb"]

in the gemspec. As long as your files are still placed in the mrblib/ folder this should make sure that the files are loaded in the given order. I had a similar problem with my gem where I did this.

[matz]

I prefer magic comment. I care about maintainability.

[palkan]

Ok. If we are going with magic comments, how they should work?

Current implementation ideologically works similar to MRI magic comments (at least, encoding, as I see here): we read source code line by line, ignore blank lines, parse magic "require" comments, scan until we find a line that do not match the magic comment (see test examples included in PR).

Not sure what to add/remove/improve.

[palkan]

Update:

• Rebased/refactored on the top of the recent master changes (moving build utils to lib/)
• Added libtest task (to test build utils)

[palkan]

🆙

Hey everyone!

Are we still interested in this feature? Maybe it's time to re-visit it?