> On 13 Apr 2018, at 3:48 AM, Mike Samuel <mikesam...@gmail.com> wrote:
>
> This seems like it could be done with decorators per
> https://github.com/tc39/proposal-decorators
> <https://github.com/tc39/proposal-decorators> without introducing a new
> keyword.
>
> @promises function sleep(...) {
> ...
> }
the problem with using decorators, object.defineproperty, and other
meta-programming features in javascript, is that no one has carefully thought
out how they can be easily debugged, especially in javascript’s quirky,
non-blocking-design context.
imagine google’s gwt, and removing most of its compile-time checks. that's
essentially the direction es6/es7/es8/etc seems to be headed (and if that’s the
case, how is it better than gwt?). is this what we want? a language with
java's meta-programming power, but lacking most of its safety-features?
how successful in getting shipped, do you think a java-project as complicated
as a typical web-project would be without compile-time meta-programming checks?
exactly ... and this is pretty much what the current state of the web-industry
is like :`(
to illustrate with code, npm has this particular meta-programming gem [1],
which leads to this surprising behavior (and corresponding real-world scenario
where this was encountered [2]):
```js
/*
* example1.js
*
* example usage:
* $ npm install npm && node example1.js
*
* example output:
* Error: Call npm.load(config, cb) before using this command.
* See the README.md or bin/npm-cli.js for example usage.
*/
/*jslint
node: true
*/
'use strict';
var command, npm;
npm = require('npm');
Object.keys(npm.commands).forEach(function (key) {
// how many people would expect this to throw an error?
command = npm.commands[key];
// rather than this?
try {
command();
} catch (ignore) {
}
});
console.log('caught all errors');
```
here's the fix that was applied (and corresponding real-world solution [3]).
but again, why should web-developers have to second-guess that arbitrary
property-accesses might throw errors (and waste valuable engineering-time
constantly guarding against them)?
```js
/*
* example2.js
*
* example usage:
* $ npm install npm && node example2.js
*
* example output:
* caught all errors
*/
/*jslint
node: true
*/
'use strict';
var command, npm, objectKeysSafe;
npm = require('npm');
objectKeysSafe = function (dict) {
/*
* this function will return a list of the dict's keys,
* that are safely accessible
*/
return Object.keys(dict).filter(function (key) {
try {
return dict[key] || true;
} catch (ignore) {
}
});
};
objectKeysSafe(npm.commands).forEach(function (key) {
// how many people would expect this to throw an error?
command = npm.commands[key];
// rather than this?
try {
command();
} catch (ignore) {
}
});
console.log('caught all errors');
```
[1] https://github.com/npm/npm/blob/v5.8.0/lib/npm.js#L112
<https://github.com/npm/npm/blob/v5.8.0/lib/npm.js#L112> - "npm/npm.js at
v5.8.0 · npm/npm"
[2] https://travis-ci.org/npmdoc/node-npmdoc-npm/builds/365262668#L1300
<https://travis-ci.org/npmdoc/node-npmdoc-npm/builds/365262668#L1300> - "Travis
CI - Test and Deploy Your Code with Confidence"
[3]
https://github.com/kaizhu256/node-apidoc-lite/blob/2017.4.12/lib.apidoc.js#L1019
<https://github.com/kaizhu256/node-apidoc-lite/blob/2017.4.12/lib.apidoc.js#L1019>
- “node-apidoc-lite/lib.apidoc.js at 2017.4.12"
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