JavaScript function overloading based on the number of parameters.
http://deploytonenyures.blogspot.com.es/2013/07/javascript-function-overloading.html
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//prompted by: http://ejohn.org/blog/javascript-method-overloading/ | |
//baseFn: function that will be used when the overloaded function is invoked with a non matching number of parameters | |
function overload(baseFn /*, overload1, overload2...*/){ | |
//returns an overload aware function | |
function buildOverload(baseFn){ | |
var overloads = { | |
"default": baseFn | |
}; | |
overloads[baseFn.length] = baseFn; | |
var overloadedFn = function(){ | |
if (!overloads[arguments.length]) | |
return overloads.default.apply(this, arguments); | |
else | |
return overloads[arguments.length].apply(this, arguments); | |
}; | |
overloadedFn.overloaded = true; | |
overloadedFn.add = function(fn){ | |
overloads[fn.length] = fn; | |
}; | |
overloadedFn.remove = function(fnLength){ | |
delete overloads[fnLength]; | |
}; | |
return overloadedFn; | |
}; | |
baseFn = baseFn || function(){}; | |
if (!baseFn.overloaded) | |
baseFn = buildOverload(baseFn); | |
overloads = [].slice.call(arguments, 1);//obtain array from arguments pseudoarray removing the first element | |
for(var i=0; i<overloads.length; i++){ | |
baseFn.add(overloads[i]); | |
} | |
return baseFn; | |
} | |
if (typeof module !== "undefined" && module.exports){ | |
exports.overload = overload; | |
} |
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var overload = require("./overload.js").overload; | |
function base(){ | |
console.log("base"); | |
} | |
function argsToString(pseudoArr){ | |
return [].join.call(pseudoArr, ", "); | |
} | |
function oneParam(param1){ | |
console.log("oneParam overload: " + argsToString(arguments)); | |
} | |
function twoParams(param1, param2){ | |
console.log("twoParams overload: " + argsToString(arguments)); | |
} | |
function threeParams(param1, param2, param3){ | |
console.log("threeParams overload: " + argsToString(arguments)); | |
} | |
var overloaded = overload(base, oneParam, twoParams); | |
overloaded(); | |
overloaded(1); | |
overloaded(1, 2); | |
console.log("no 3 params overload, so it will use the default"); | |
overloaded(1, 2, 3); | |
overload(overloaded, threeParams); | |
//the above is right equivalent to this: | |
//overloaded.add(threeParams); | |
console.log("3 params overload has been added:"); | |
overloaded(1, 2, 3); | |
console.log("no 5 params overload, so it will use the default"); | |
overloaded(1, 2, 3, 4, 5); | |
overloaded.remove(3); | |
console.log("3 params overload has been removed"); | |
console.log("no 3 params overload, so it will use the default"); | |
overloaded(1, 2, 3); | |
overloaded.add(threeParams); | |
console.log("3 params overload has been added again"); | |
overloaded(1, 2, 3); |
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