deprecated.js

/**
 * Copyright 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule deprecated
 * @flow
 */

'use strict';

var lowPriorityWarning = require('lowPriorityWarning');

/**
 * This will log a single deprecation notice per function and forward the call
 * on to the new API.
 *
 * @param {string} fnName The name of the function
 * @param {string} newModule The module that fn will exist in
 * @param {string} newPackage The module that fn will exist in
 * @param {*} ctx The context this forwarded call should run in
 * @param {function} fn The function to forward on to
 * @return {function} The function that will warn once and then call fn
 */
function deprecated<T: Function>(
  fnName: string,
  newModule: string,
  newPackage: string,
  ctx: mixed,
  fn: T,
): T {
  var warned = false;
  if (__DEV__) {
    var newFn = function() {
      lowPriorityWarning(
        warned,
        /* eslint-disable no-useless-concat */
        // Require examples in this string must be split to prevent React's
        // build tools from mistaking them for real requires.
        // Otherwise the build tools will attempt to build a '%s' module.
        'React.%s is deprecated. Please use %s.%s from require' +
          "('%s') " +
          'instead.',
        fnName,
        newModule,
        fnName,
        newPackage,
      );
      /* eslint-enable no-useless-concat */
      warned = true;
      return fn.apply(ctx, arguments);
    };
    // We need to make sure all properties of the original fn are copied over.
    // In particular, this is needed to support PropTypes
    Object.assign(newFn, (fn: Object));

    // Flow is not smart enough to figure out that newFn is of the same type as
    // fn. Since we don't want to lose out the type of the function, casting
    // to any and force flow to use T.
    return ((newFn: any): T);
  }

  return fn;
}

module.exports = deprecated;