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var createWrapper = require('../internal/createWrapper'),
replaceHolders = require('../internal/replaceHolders'),
restParam = require('./restParam');
/** Used to compose bitmasks for wrapper metadata. */
var BIND_FLAG = 1,
PARTIAL_FLAG = 32;
/**
* Creates a function that invokes `func` with the `this` binding of `thisArg`
* and prepends any additional `_.bind` arguments to those provided to the
* bound function.
*
* The `_.bind.placeholder` value, which defaults to `_` in monolithic builds,
* may be used as a placeholder for partially applied arguments.
*
* **Note:** Unlike native `Function#bind` this method does not set the "length"
* property of bound functions.
*
* @static
* @memberOf _
* @category Function
* @param {Function} func The function to bind.
* @param {*} thisArg The `this` binding of `func`.
* @param {...*} [partials] The arguments to be partially applied.
* @returns {Function} Returns the new bound function.
* @example
*
* var greet = function(greeting, punctuation) {
* return greeting + ' ' + this.user + punctuation;
* };
*
* var object = { 'user': 'fred' };
*
* var bound = _.bind(greet, object, 'hi');
* bound('!');
* // => 'hi fred!'
*
* // using placeholders
* var bound = _.bind(greet, object, _, '!');
* bound('hi');
* // => 'hi fred!'
*/
var bind = restParam(function(func, thisArg, partials) {
var bitmask = BIND_FLAG;
if (partials.length) {
var holders = replaceHolders(partials, bind.placeholder);
bitmask |= PARTIAL_FLAG;
}
return createWrapper(func, bitmask, thisArg, partials, holders);
});
// Assign default placeholders.
bind.placeholder = {};
module.exports = bind;
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