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var baseRest = require('./_baseRest'),
createWrap = require('./_createWrap'),
getHolder = require('./_getHolder'),
replaceHolders = require('./_replaceHolders');
/** Used to compose bitmasks for function metadata. */
var WRAP_BIND_FLAG = 1,
WRAP_BIND_KEY_FLAG = 2,
WRAP_PARTIAL_FLAG = 32;
/**
* Creates a function that invokes the method at `object[key]` with `partials`
* prepended to the arguments it receives.
*
* This method differs from `_.bind` by allowing bound functions to reference
* methods that may be redefined or don't yet exist. See
* [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern)
* for more details.
*
* The `_.bindKey.placeholder` value, which defaults to `_` in monolithic
* builds, may be used as a placeholder for partially applied arguments.
*
* @static
* @memberOf _
* @since 0.10.0
* @category Function
* @param {Object} object The object to invoke the method on.
* @param {string} key The key of the method.
* @param {...*} [partials] The arguments to be partially applied.
* @returns {Function} Returns the new bound function.
* @example
*
* var object = {
* 'user': 'fred',
* 'greet': function(greeting, punctuation) {
* return greeting + ' ' + this.user + punctuation;
* }
* };
*
* var bound = _.bindKey(object, 'greet', 'hi');
* bound('!');
* // => 'hi fred!'
*
* object.greet = function(greeting, punctuation) {
* return greeting + 'ya ' + this.user + punctuation;
* };
*
* bound('!');
* // => 'hiya fred!'
*
* // Bound with placeholders.
* var bound = _.bindKey(object, 'greet', _, '!');
* bound('hi');
* // => 'hiya fred!'
*/
var bindKey = baseRest(function(object, key, partials) {
var bitmask = WRAP_BIND_FLAG | WRAP_BIND_KEY_FLAG;
if (partials.length) {
var holders = replaceHolders(partials, getHolder(bindKey));
bitmask |= WRAP_PARTIAL_FLAG;
}
return createWrap(key, bitmask, object, partials, holders);
});
// Assign default placeholders.
bindKey.placeholder = {};
module.exports = bindKey;
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