javascriptcoco

How to generate functions in a loop in coco?


I would like to generate functions in a loop:

for own k, v in t
  ctor::[k] = ->
    v(...)
    @

However, coco seems to generate just one function and reuse it:

var k, v, __ref, __own = {}.hasOwnProperty;
for (k in __ref = t) if (__own.call(__ref, k)) {
  v = __ref[k];
  ctor.prototype[k] = __fn;
}
function __fn(){
  v.apply(this, arguments);
  return this;
}

How to change the coco script to make the output following:

var k, v, __ref, __own = {}.hasOwnProperty;
for (k in __ref = t) if (__own.call(__ref, k)) {
  v = __ref[k];
  ctor.prototype[k] = function() {
    v.apply(this, arguments);
    return this;
  }
}

CLARIFICATION: With coco I mean this language: http://satyr.github.com/coco/ (a coffeescript fork).


Solution

  • It's a feature. Writing function directly within a loop should be almost always avoided. JSLint forbids it saying "Don't make functions within a loop."

    Your code in particular has a scope bug (all v in the dynamically created methods will refer to the same value). You should use let binding there:

    for own k, v in t
      let
        ctor::[k] = ->
          v ...
          this
    

    which compiles to:

    var k, v, __ref, __own = {}.hasOwnProperty;
    for (k in __ref = t) if (__own.call(__ref, k)) {
      v = __ref[k];
      (__fn.call(this, k, v));
    }
    function __fn(k, v){
      ctor.prototype[k] = function(){
        v.apply(this, arguments);
        return this;
      };
    }