then

Domenic Denicola domenic at domenicdenicola.com
Fri Nov 9 11:57:14 PST 2012


The idea is to not do the processing if the JSON parsing fails.

From: Cryptic Swarm [mailto:crypticswarm at gmail.com]
Sent: Friday, November 9, 2012 11:55
To: Domenic Denicola
Cc: es-discuss at mozilla.org
Subject: Re: then

The following should work? Finally expects a block statement, so need to wrap it in { }...

var info, processed;
try {
    info = JSON.parse(json);
} catch (exception) {
    console.log("Information JSON malformed.");
} finally { try {
    processed = process(info);
} catch (exception) {
    console.log("Error processing information.");
}}
On Fri, Nov 9, 2012 at 1:46 PM, Domenic Denicola <domenic at domenicdenicola.com<mailto:domenic at domenicdenicola.com>> wrote:
The recent promise discussion prompted me to recall the following musing/proposal from Kris Kowal:

https://github.com/kriskowal/q/wiki/On-Exceptions

In short, there's a common code pattern that you can do with promises that you can't do with synchronous code. The proposal is for a language extension `then` that would allow synchronous code like this:

var info, processed;
try {
    info = JSON.parse(json);
} catch (exception) {
    console.log("Information JSON malformed.");
} then {
    processed = process(info);
} catch (exception) {
    console.log("Error processing information.");
}

Since seeing this, I've run into a lot of situations where a `then` would come in handy. I wanted to see if anyone else thought this was a great idea, and if it has any chance as an ES7-level proposal.

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