removeFile plugin API for allowing plugins to participate in removeCombined

[jrburke]

Suggested by @peol in requirejs/text#33: allow plugins, like the text plugin, to remove resources that are part of a build.

Maybe add a new build API a plugin can implement to do this. First thought:

removeFile(pluginId, resourceId, remove) where:

• pluginId: String. Plugin ID
• resourceId: The normalized resource ID
• remove: Function. Pass it a string of a file name to remove.

Not sure if this is enough. For instance, a require.toUrl maybe useful?

It should be called when removeCombined is in effect, and it would need docs on the plugins.html page.

[spalger]

I personally don't see why each plugin would need to implement the removal logic separately. I think it would be simpler if new property functions were included on write, maybe:

• write.fileContents(filePath|filePath[], contents)
• write.fileContentsAsModule(filePath|filePath[], moduleName, contents)

Then when r.js is wrapping up it's optimizations it can unlink all the filesPaths it received following the same logic it uses for removing combined scripts. From the plugin author's perspective it wouldn't require too many changes. In the context of the text plugin it could look something like this:

finishLoad: function (name, url, strip, content, onLoad) {
  ...
  buildMap[name] = {
    filename: url,
    content: content
  };
  ...
},
...
write: function (pluginName, moduleName, write, config) {
  ...
  write.fileContentsAsModule(
    buildMap[name].filename,
    pluginName + "!" + moduleName,
    "define(function () { return '" +
      content +
    "';});\n"
  );
  ...
}

It might even make sense to just add filePath as an optional argument to write and it's siblings...

Based on feedback I'd be happy to work this into a pull request. Disclaimer, I am not _at all_ familiar with the magic which occurs inside r.js, but I do ❤️ it.

[jrburke]

The problem is that plugin dependency IDs are opaque to the loader -- it does not try to interpret what they mean. For a given dependency ID like 'pluginId!something-here', the 'something-here' part could be anything, a pointer to a more than one file, in the case of a 'has!some-test?ok.html:notok.html' case, or not even a file, like something that waits for an onload event from an img tag.

[spalger]

This API would only be used for plugins that do resolve to file(s) and would just be a simple way for them to declare that "I included this file so it can be deleted if that's what the user wants".