ELC-TYPEY

Some helpers and bits 'n' bobs for runtime type checking.

You'll probably never want to use this library unless you have some very wierd and specific legacy/refactoring to do.

If you are using this on a brand new project you should probably look at ES7 decorators or sweet-js macros instead.

Usage

var type = require('elc-typey');

var typeCheck = type(constructor || "string" || undefined [, ...]);

var stuff = function(user, name, age){
  typeCheck(arguments);
}

type takes a variable number of arguments, each of which should either be a

• constructor function : if supplied then an instanceof test will be used.
• string : if supplied then a typeof test will be used and compared against the supplied string.
• undefined || "*" : if supplied then no type checking will be used.

The function returned by type() should then be called with the arguments you wish to type check.

elc-typey exports some aliases to shorten function signatures

var type = = require('elc-typey');

console.log(type);
{ [Function: typeCheck]
  fn: 'function',
  str: 'string',
  bool: 'boolean',
  num: 'number',
  obj: 'object',
  any: '*'
}

var typeCheck = type(type.fn, type.bool, '*')

This library will not modify the arguments in anyway before passing them through to your original function. (combinators are great things) (except ycombinator - that is a bad thing™)

Examples

type = require('elc-typey')

class Accounts

    constructor: type(Date, Date) (start, end)->

        @_start = somethingCool(start)
        @_date = somethingElseCool(end)

var type = require('elc-typey');

var User = function User();

var typeCheck = type(User, Date)

var myPlainFunction = function(user, date){
    //some logic and stuff
}

var typeCheckedFunc = typeCheck(myPlainFunction);

// this won't throw
typeCheckedFunc(new User(), new Date());

// this will throw
typeCheckedFunc('cat', new Date());
// throws : "Argument at position 0 was instance of 'String' but expected 'User'"