Lodash CreateWrapper

var createWrapper = require('lodash._createwrapper');

var createWrapper = require('lodash._createwrapper');

// Example: Create a simple bind wrapper
function greet(greeting, name) {
  return greeting + ', ' + name;
}
var obj = { greeting: 'Hello' };

// Create wrapper with bind flag (bitmask value 1 for BIND_FLAG)
var boundGreet = createWrapper(greet, 1, obj);
var result = boundGreet('Hello', 'World'); // 'Hello, World'

/**
 * Creates a function wrapper with behavioral modifications
 * @param {Function|string} func - The function or method name to wrap
 * @param {number} bitmask - Bitmask of flags controlling wrapper behavior
 * @param {*} [thisArg] - Optional 'this' binding for the wrapper
 * @param {Array} [partials] - Optional arguments to prepend
 * @param {Array} [holders] - Optional placeholder indexes for partials
 * @param {Array} [argPos] - Optional argument positions for reordering
 * @param {number} [ary] - Optional arity cap
 * @param {number} [arity] - Optional arity of the function
 * @returns {Function} The new wrapped function
 * @throws {TypeError} When func is not a function and BIND_KEY_FLAG is not set
 */
function createWrapper(func, bitmask, thisArg, partials, holders, argPos, ary, arity);

// Flag values (internal constants, use numeric values directly):
// BIND_FLAG = 1        - Bind 'this' context
// BIND_KEY_FLAG = 2    - Bind method by key name
// CURRY_BOUND_FLAG = 4 - Curry bound functions
// CURRY_FLAG = 8       - Enable currying
// CURRY_RIGHT_FLAG = 16    - Enable right-currying
// PARTIAL_FLAG = 32        - Partial application (left)
// PARTIAL_RIGHT_FLAG = 64  - Partial application (right)
// REARG_FLAG = 128     - Argument reordering
// ARY_FLAG = 256       - Arity capping

var createWrapper = require('lodash._createwrapper');

// Bind example (bitmask: 1)
var obj = { name: 'John' };
function sayHello() { return 'Hello, ' + this.name; }
var boundSayHello = createWrapper(sayHello, 1, obj);
// boundSayHello() returns "Hello, John"

// Partial application example (bitmask: 32)
function add(a, b, c) { return a + b + c; }
var addFive = createWrapper(add, 32, null, [5]);
// addFive(2, 3) returns 10

// Currying example (bitmask: 8)
function multiply(a, b, c) { return a * b * c; }
var curriedMultiply = createWrapper(multiply, 8);
// curriedMultiply(2)(3)(4) returns 24

// Arity capping example (bitmask: 256)
function variadicSum() {
  var sum = 0;
  for (var i = 0; i < arguments.length; i++) {
    sum += arguments[i];
  }
  return sum;
}
var binarySum = createWrapper(variadicSum, 256, null, null, null, null, 2);
// binarySum(1, 2, 3, 4) returns 3 (only uses first 2 arguments)

// Combined flags example (bitmask: 1 | 32 = 33)
function greetWithPrefix(prefix, name) { 
  return prefix + ', ' + name + ' from ' + this.location; 
}
var obj = { location: 'Paris' };
var parisGreeter = createWrapper(greetWithPrefix, 33, obj, ['Bonjour']);
// parisGreeter('Marie') returns "Bonjour, Marie from Paris"

// This will throw TypeError - not a function without BIND_KEY_FLAG
try {
  createWrapper("not a function", 1); // BIND_FLAG (1) without BIND_KEY_FLAG (2)
} catch (e) {
  console.log(e instanceof TypeError); // true
  console.log(e.message); // "Expected a function"
}

// This is valid (BIND_KEY_FLAG allows string method names)
var wrapper = createWrapper("toString", 2, {}); // BIND_KEY_FLAG = 2