my_functions.js

/*global _ */

/*jslint
  browser : true, continue : true,
  devel   : true, indent   : 2,    maxerr   : 50,
  newcap  : true, nomen    : true, plusplus : true,
  regexp  : true, sloppy   : true, vars     :false,
  white   : true
*/

var _ = require('underscore');
var my_functions = {
  fail: function(thing) { throw new Error(thing); },
  existy: function(x) { return x != null; },
  truthy: function(x) { return (x !== false) && my_functions.existy(x); },

  doWhen: function(cond, fun) {
    if(my_functions.truthy(cond)) { return fun(); }
    return undefined;
  },

  invoker: function(name, method) {
    return function(target /* */) {
      if(!my_functions.existy(target)) { my_functions.fail('Must provide a target'); }

      var
        args         = _.rest(arguments),
        targetMethod = target[name];

      return my_functions.doWhen((my_functions.existy(targetMethod) && method === targetMethod), function() {
        return targetMethod.apply(target, args);
      });
    };
  },

  makeUniqueStringFunction: function(start) {
    var counter = start;
    return function(prefix) {
      return [prefix, counter++].join('');
    };
  },

  checker: function(/* */) {
    var validators = _.toArray(arguments);

    return function(obj) {
      return _.reduce(validators, function(errs, check) {
        if(check(obj)) { return errs; }
        return _.chain(errs).push(check.message).value();
      }, []);
    };
  },

  validator: function(message, fun) {
    var f = function(/* */) {
      return fun.apply(fun, arguments);
    };

    f.message = message;
    return f;
  }
};

module.exports = my_functions;