问题描述
Let's take stdin.on as an example. Callbacks to stdin.on stack, so if I write (in CoffeeScript)
stdin = process.openStdin()
stdin.setEncoding 'utf8'
stdin.on 'data', (input) -> console.log 'One'
stdin.on 'data', (input) -> console.log 'Two'
then every time I hit return at the prompt, I get
One
Two
My question is, is there any way to remove/replace a callback once bound? Or is the only approach to bind a proxy callback and manage state myself?
You can use removeListener(eventType, callback) to remove an event, which should work with all kinds of emitters.
Example from the API docs:
var callback = function(stream) {
console.log('someone connected!');
};
server.on('connection', callback);
// ...
server.removeListener('connection', callback);
So you need to have a variable that holds a reference to the callback, because obviously, it's otherwise impossible to tell which callback you want to have removed.
EDIT
Should be someone like this in CS:
stdin = process.openStdin()
stdin.setEncoding 'utf8'
logger = (input) -> console.log 'One'
stdin.on 'data', logger
stdin.removeListener 'data', logger
stdin.on 'data', (input) -> console.log 'Two'
See: http://nodejs.org/docs/latest/api/events.html#emitter.removeListener
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