Only terseness/consistency. It's easy for a module to add a bunch of stuff
to Function.prototype, and it's then just there with a consistent name.
For global functions to be available you'd have to require them, though
this gives you flexibility on the short names, e.g.
var xie = require("callback-helpers").exitOnError;
On Tuesday, March 19, 2013 4:59:58 PM UTC-7, stagas wrote:
>
> What's the difference from a someFunction(foo, xie(2, callbackFn))
> pattern that doesn't pollute Function.prototype?
>
> 2013/3/20 Ken <[email protected] <javascript:>>:
> > I've been writing a bunch of shell-script-like node scripts lately.
> These
> > mostly call a series of async functions that take the usual function
> (error,
> > data) { ... } callback, and generally they handle any error along the
> way by
> > logging it and exiting. Here's a naive example using aws-sdk to make a
> > couple EC2 API calls in serial
> >
> > var AWS = require("aws-sdk");
> >
> > var ec2 = new AWS.EC2.Client();
> >
> > ec2.runInstances({ ... }, function (error, runInstancesResponse) {
> > if (error) {
> > console.log(error);
> > process.exit(1);
> > } else {
> > // ... get the instanceIds from response as input to createTags
> > ec2.createTags({ ... }, function (error, createTagsResponse) {
> > if (error) {
> > console.log(error);
> > process.exit(2);
> > } else {
> > // ... do further processing ...
> > }
> > });
> > }
> > });
> >
> > As you can see a lot of the total lines are just totally boilerplate if
> > (error) barf. Since we've got a functional language here, pretty easy
> to
> > encapsulate that, e.g. with this
> >
> > Function.prototype.xie = Function.prototype.exitIfError = function
> > (exitCode) {
> > var f = this;
> > return function (error, data) {
> > if (error) {
> > console.log(error);
> > process.exit(exitCode || 1);
> > } else {
> > f.call(this, data);
> > }
> > };
> > }
> >
> > our code collapses to just
> >
> > ec2.runInstances({ ... }, function (runInstancesResponse) {
> > // ... get the instanceIds from response as input to createTags
> > ec2.createTags({ ... }, function (createTagsResponse) {
> > // ... do further processing ...
> > }.xie(2));
> > }.xie(1));
> >
> > Which feels a lot more readable to me. Is there precedent for this
> > technique? A name for it? Any well known modules that implement it? Any
> > obvious horrible side effects? Clearly not applicable to sophisticated
> > error handling, but for this basic "it all works or just give up" kind
> of
> > thing it seems handy. Could add "abort if error", "throw if error",
> "emit
> > if error" flavors as well.
> >
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