A generic function definition and multi-dispatch library for JavaScript.
Multi-dispatch generic functions support the selection and execution of a function based on the types and number of arguments.
npm install js-generics
The index.js and package.json files are compatible with node-require so that js-generics can be served directly to the browser from the node-modules/js-generics directory when using node Express.
Multi-dispatch generic functions support the selection and execution of a function based on the types and number of arguments. A common use is supporting mathematical operations on different types of objects. For example:
var sum = generic(function() { throw new Error("can't sum " + JSON.stringify(arguments)); } )
.method("number","number",
function(arg1,arg2) { return arg1 + arg2; })
.method(function(arg) { return arg instanceof Array;},"number",
function(arg1, arg2) { arg1.forEach(function(item,i) { arg1[i] += arg2; }); return arg1; });
In the example above the generic function sum is defined to throw an error if no matching dispatch can be found. Matching dispatches have two arguments of type number or a first argument of kind array and a second of type number.
The general form of usage is:
generic(<default function>).method(<type matcher>[,<type matcher>...],<function to call>)[.method(<type matcher>[,<type matcher>...],<function to call>),...]
<default function> - This function is called if no matching dispatches are found. It can take any form and is called as .apply(this,arguments). As a result generic functions can be included as methods on objects.
<type matcher> - These should be primitive type names or functions. If a function, it's sole responsibility is to return true or false if the argument type is correct. The number of <type matcher> must match the number of arguments to <function to call>, or the last <type matcher> must be the special value generic.VARGS.
<function to call> - This function does the desired work. It is called as <type matcher>.apply(this,arguments).
.method calls can be chained and the last matching method is the one invoked by the dispatcher.
v0.0.6 2016-01-03 Corrected markdown issues is README.
v0.0.5 2016-01-03 Added unit tests and documentation.
v0.0.4 2015-12-13 Codacy improvements
v0.0.3 2015-12-13 Initial public commit.
MIT License - see LICENSE file