Introduction
Ever been to callback hell? Here, I propose another solution. A syntax sugaring called Dotcall. I developed it while working on my various Node.js projects because I realized I spend too much time on very simple tasks only because callback syntax is so unfriendly. It is not rocket science, it is just time consuming to get all the curly and less curly braces in place. I post it here because it could be used by someone, maybe you will report issues or even help make it better with your forks or commits. The source is here https://github.com/exebook/dotcall.
Theory
The theory behind it is this:
- Most of the time, the result of an asynchronous function is not used, and after it was called, the upper functions also exit immediately. Although sometimes the upper function can do something after it called the first
async(callback), usually it does nothing and returns. Sometimes, the asynchronous function could return something useful, but most of the time, it just returns undefined and the real stuff is returned with callback(result). - When the above situation is true, the special syntax sugar can be applied.
There is some discussion of this theory on StackOverflow: http://stackoverflow.com/questions/27102432/automatic-callback-ladder-creator
Syntax
The syntax of dotcall is very simple, when the call's brace is preceeded with a dot .(, then the call is converted (hence the name):
var a = f.()
console.log(a)
Is replaced with:
f(function(DOTCALL1) { var a = DOTCALL1
console.log(a)
})
In case your callback uses more than one parameter, there is an extended syntax, called double colon syntax.
redis.set.('a', 12345)
redis.get.('a' :: err, data)
if (err) console.log(err)
console.log(data)
Another case of double colon notation is to specify the useful argument number like this:
redis.set.('a', 12345)
console.log(redis.get.('a' :: 2))
The above outputs 12345, because Redis function get(err, data) uses data as a second parameter.
Implementation
Instead of using complex JavaScript parser, I decided to use a naive approach and simple string manipulation with
.IndexOf,
.replace,
.substr and
RegExp. So the module is fast and small. The whole source code is under 300 lines, and in fact most of that is comments. Since the approach is naive, of course it will only handle most stright forward situations, but that could cover almost everything I need to talk to DB or do some async file or network operations.
install with npm
npm install dotcall
About Me
My name is Yakov, I am from Russia. I have been working for many years on Exebook Self-Publisher, which is closed now. Later, I created Deodar file manager and text editor in Node.js+OpenGL. You can find it at https://github.com/exebook/deodar under Unlicense license, but it is not localized to English. Now I am working for uteeter.com and ksana.tw. I program mostly in JavaScript.
