diff --git a/README.md b/README.md new file mode 100644 index 0000000..88fa534 --- /dev/null +++ b/README.md @@ -0,0 +1,60 @@ +# promisify-simple-callback + +Promisifies a function that expects a callback with a single (result) argument - in other words, a callback that looks like `function(result) { ... }` - in what should be a reasonably performant manner. + +Because sometimes, a module just doesn't conform to the Node.js callback convention. + +## License + +[WTFPL](http://www.wtfpl.net/txt/copying/) or [CC0](https://creativecommons.org/publicdomain/zero/1.0/), whichever you prefer. A donation and/or attribution are appreciated, but not required. + +## Donate + +My income consists largely of donations for my projects. If this module is useful to you, consider [making a donation](http://cryto.net/~joepie91/donate.html)! + +You can donate using Bitcoin, PayPal, Flattr, cash-in-mail, SEPA transfers, and pretty much anything else. + +## Contributing + +Pull requests welcome. Please make sure your modifications are in line with the overall code style, and ensure that you're editing the files in `src/`, not those in `lib/`. + +Build tool of choice is `gulp`; simply run `gulp` while developing, and it will watch for changes. + +Be aware that by making a pull request, you agree to release your modifications under the licenses stated above. + +## Usage + +```javascript +var Promise = require("bluebird"); +var promisifySimpleCallback = require("promisify-simple-callback"); + +/* Pretend that brokenAsyncMethod comes from a third-party library. */ +function brokenAsyncMethod(someArg, options, cb) { + doSomething(options, function(err, result) { + cb(result); + }) +} + +/* Promisify it! */ +var promisifiedAsyncMethod = promisifySimpleCallback(brokenAsyncMethod, [null, {}]); + +/* Now we can use it normally. */ +Promise.try(function() { + return promisifiedAsyncMethod("foobar"); +}).then(function(result) { + console.log("Done!", result); +}); +``` + +## API + +### promisifySimpleCallback(func, [defaults]) + +Promisifies the given `func`. The promisified method will also catch any synchronous errors, and propagate them as rejections. + +You can also specify default argument values; often, there are optional arguments that come before the callback, and by specifying default values, you can make these arguments *really* optional. + +Because promisification works by appending a callback at the end of the arguments list, you would otherwise have to include all the optional arguments just to make sure the callback ends up in the right place. + +* __func__: The callback-expecting function to promisify. +* __defaults__: *Optional.* An array of default arguments to fill in. Any argument for which you specify `null` will be skipped - that is, it will be left exactly as is. This means that, for an unspecified argument, it is left to `undefined`. diff --git a/gulpfile.js b/gulpfile.js new file mode 100644 index 0000000..f35e142 --- /dev/null +++ b/gulpfile.js @@ -0,0 +1,24 @@ +var gulp = require('gulp'); + +var gutil = require('gulp-util'); +var babel = require('gulp-babel'); +var cache = require('gulp-cached'); +var remember = require('gulp-remember'); +var plumber = require('gulp-plumber'); + +var source = ["src/**/*.js"] + +gulp.task('babel', function() { + return gulp.src(source) + .pipe(plumber()) + .pipe(cache("babel")) + .pipe(babel({presets: ["es2015"]}).on('error', gutil.log)).on('data', gutil.log) + .pipe(remember("babel")) + .pipe(gulp.dest("lib/")); +}); + +gulp.task('watch', function () { + gulp.watch(source, ['babel']); +}); + +gulp.task('default', ['babel', 'watch']); \ No newline at end of file diff --git a/index.js b/index.js new file mode 100644 index 0000000..507257b --- /dev/null +++ b/index.js @@ -0,0 +1,3 @@ +'use strict'; + +module.exports = require("./lib"); \ No newline at end of file diff --git a/lib/index.js b/lib/index.js new file mode 100644 index 0000000..0c4f939 --- /dev/null +++ b/lib/index.js @@ -0,0 +1,37 @@ +'use strict'; + +var Promise = require("bluebird"); + +module.exports = function (method) { + var defaults = arguments.length <= 1 || arguments[1] === undefined ? [] : arguments[1]; + + return function () { + var _arguments = arguments, + _this = this; + + return new Promise(function (resolve, reject) { + var args = new Array(Math.max(_arguments.length, defaults.length) + 1); + + for (var i = 0; i < args.length; ++i) { + args[i] = _arguments[i]; + } + + if (_arguments.length - 1 < defaults.length) { + for (var i = _arguments.length - 1; i < defaults.length; i++) { + if (defaults[i] != null) { + args[i] = defaults[i]; + } + } + } + + args[args.length - 1] = function (result) { + resolve(result); + }; + + console.log(args); + + // Synchronous errors are caught and propagated by Bluebird's `new Promise` already. + method.apply(_this, args); + }); + }; +}; \ No newline at end of file diff --git a/package.json b/package.json new file mode 100644 index 0000000..42d2d07 --- /dev/null +++ b/package.json @@ -0,0 +1,32 @@ +{ + "name": "promisify-simple-callback", + "version": "1.0.0", + "description": "Promisifies a function that expects a callback with a single (result) argument", + "main": "index.js", + "scripts": { + "test": "echo \"Error: no test specified\" && exit 1" + }, + "repository": { + "type": "git", + "url": "git://github.com/joepie91/node-promisify-simple-callback" + }, + "keywords": [ + "promisify", + "bluebird", + "promise" + ], + "author": "Sven Slootweg", + "license": "WTFPL", + "dependencies": { + "bluebird": "^3.3.3" + }, + "devDependencies": { + "babel-preset-es2015": "^6.6.0", + "gulp": "^3.9.1", + "gulp-babel": "^6.1.2", + "gulp-cached": "^1.1.0", + "gulp-plumber": "^1.1.0", + "gulp-remember": "^0.3.0", + "gulp-util": "^3.0.7" + } +} diff --git a/src/index.js b/src/index.js new file mode 100644 index 0000000..49172b3 --- /dev/null +++ b/src/index.js @@ -0,0 +1,33 @@ +'use strict'; + +const Promise = require("bluebird"); + +module.exports = function(method, defaults = []) { + return function() { + return new Promise((resolve, reject) => { + var args = new Array(Math.max(arguments.length, defaults.length) + 1); + + for(var i = 0; i < args.length; ++i) { + args[i] = arguments[i]; + } + + if (arguments.length - 1 < defaults.length) { + for(var i = arguments.length - 1; i < defaults.length; i++) { + if (defaults[i] != null) { + args[i] = defaults[i]; + } + } + } + + args[args.length - 1] = function(result) { + resolve(result); + } + + console.log(args); + + // Synchronous errors are caught and propagated by Bluebird's `new Promise` already. + method.apply(this, args); + }) + } + +} \ No newline at end of file