Implement .gulprc support

[phated]

Implement through use of gulpjs/liftoff#8 which has outstanding PR at gulpjs/liftoff#67

[phated]

Support for this in Liftoff was just published as 2.3.0

@sttk would you like to implement it for gulp?

[sttk]

@phated Yes, I'd like to implement it.

I want to use key chain style for gulprc as below, but it is not popular as a configuration file. Can I use this style and the module customerizer for this?

cli.flags.cwd = 'path/of/cwd';
cli.flags.logLevel = 4; 

colors.tasks.tree.task.name = s => chalk.bold(chalk.blue(s));
colors.tasks.tree.task.description = chalk.black;

[phated]

@sttk I don't think the configuration file needs to be that complex. I also think that attempting the implementation with the most simple thing first is the correct approach (so don't start with colors). I think the easiest thing to support would be a top level description property as outlined in #70. The .gulprc would then look like:

{
  "description": "My sample description for gulpfile"
}

It could also be a node module that used module.exports = ... because we will just be using require to load the file.

[sttk]

@phated I got it. And I agree that we should start with the most simple configuration.

... we will just be using require to load the file.

require and rechoir can't get the extension "rc" from filename ".gulprc". So they load the file as a js file.

For autoloading .gulprc with rechoir, we need to do follwing two things:

1. Create a new loader for JSON file. This code would do a thing like module.exports = JSON.parse(fs.readFileSync(fp, opts)) and something similar to module.load except resolving extension.
2. Change extension module in rechoir to enable to get the extension "rc" from the filename ".gulprc". This would be made possible by seeking a matching tail in rechoir's argument config.

[sttk]

@phated Can I change rechoir as above?

[phated]

Oh, you are right that .gulprc won't work out of the box with require. Let's just support .gulp.js, etc (all the extensions we already support).

[sttk]

I got it. I'll implement so.

[sttk]

@phated I determined that the configuration file name is .gulprc.*, and I'm planning the following features about the configuration file.

• Load and merge configuration files in home directory, project directory, current work directory if exists.
• Print configurations in JSON format by --output-config flag.
• Load and merge configuration files by --config or -c flag.
• Ignore configuration files by --ignore-config flag, except files specified by --config flag.

[sttk]

And I implemented the first and second check items in my repository.

sttk/gulp-cli#support_gulprc ( Comparing changes )

Please point out about the features, the implementations, etc.

[sttk]

@phated I've implemented all features above.