create a custom grunt task for processing files

Question

I am trying to write a grunt task that would go over a set of input files and run a transformation on each file. let's assume the input files are given by *.in and for each of them the task will create an .out file.

From what I read, it seems that the config should look something like this

grunt.initConfig({
    my_task: {
        src: 'C:/temp/*.in',
        dest: 'C:/temp/output/*.out'
    }
});

and the task registration should be:

grunt.registerTask('my_task', 'iterate files', function() {
    //iterate files.
});

I cannot figure out how to make grunt send me the list of files and iterate over them.

Any idea how to do it?

Solution

This is what I ended doing and what solved my problem. for the task configuration I did the following:

  grunt.initConfig({
    convert_po: {
      build: {
        src: 'C:/temp/Locale/*.po',
        dest: 'C:/temp/Locale/output/'
      }
    }
  });

and this is the task's implementation:

  grunt.registerMultiTask('convert_po', 'Convert PO files to JSON format', function() {
var po = require('node-po');
var path = require('path');

grunt.log.write('Loaded dependencies...').ok();

//make grunt know this task is async.
var done = this.async();

var i =0;
this.files.forEach(function(file) {
  grunt.log.writeln('Processing ' + file.src.length + ' files.');

  //file.src is the list of all matching file names.
  file.src.forEach(function(f){ 
    //this is an async function that loads a PO file
    po.load(f, function(_po){
      strings = {};
        for (var idx in _po.items){
            var item = _po.items[idx];
            strings[item.msgid] = item.msgstr.length == 1 ? item.msgstr[0] : item.msgstr;
        }
        var destFile = file.dest + path.basename(f, '.po') + '.json';
        grunt.log.writeln('Now saving file:' + destFile);
        fs.writeFileSync(destFile, JSON.stringify(strings, null, 4));

        //if we processed all files notify grunt that we are done.
        if( i >= file.src.length) done(true);
    });
  });
});
});