Error when pygments not installed

[fortes]

The library throws if pygments isn't installed on the system, with no way to catch the error.

[pksunkara]

Are you sure?

https://github.com/pksunkara/pygments.js/blob/master/pygments.js#L44 makes sure the error returned in the callback.

[fortes]

@pksunkara Not sure if that link is to the wrong line, but it definitely doesn't error check.

If pygments isn't installed, the following line will throw:

pyg.stdin.write(target);

Because the stdin stream won't work without a real process running. According to the Node docs, the code should check for a failed exec as follows:

var spawn = require('child_process').spawn,
    child = spawn('bad_command');

child.stderr.setEncoding('utf8');
child.stderr.on('data', function (data) {
  if (/^execvp\(\)/.test(data)) {
    console.log('Failed to start child process.');
  }
});

Fixing this will likely require changing the API signature of the colorize callback, which currently expects a single argument.

[pksunkara]

Actually, the module is designed to do that.

Generally, this module is used for building apps which highlight stuff. So, if pygmentize command is not available, highlighting should throw an error and stop the program completely.

[fortes]

I must be missing something: How does one catch the error so the program doesn't crash? Try/catch around the colorize call doesn't work due to async.

[pksunkara]

Can you show me code? I want to see what exactly you are trying to do.

[fortes]

var highlight = require("pygments").colorize;

try {
  highlight('puts "Hello World"', 'ruby', 'console', console.log);
}
catch (error) {
  console.error("Error thrown by pygments");
}

Here is the error that is thrown if pygmentize can't be found:

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: write EPIPE
    at errnoException (net.js:904:11)
    at Object.afterWrite (net.js:720:19)

[pksunkara]

Yes, this was intentional. I didn't want users to catch the error. Though, It could have a better error message.

[fortes]

I can't understand why you would want the program to crash. Why not allow developers to catch the error and prevent hard crashes?

[pksunkara]

I looked at the other issues you referenced above. I understand what you are trying to do and will support returning error. Are you interesting in doing the pull request?

[fortes]

Sure, however the problem is that this will change the method signature for the colorize callback. In order to fit node style, the first argument will be the error object. Currently, the callback just directly returns the highlighted code.

If you're OK with changing the signature, then I can do the pull request.

[pksunkara]

Yeah, I will just tag it as version v1.0.0

[moroshko]

Any update on this?

[puneetratan]

Hi, I am trying to run this module and getting error
Code: var highlight = require("pygments").colorize;

var highlight = require("pygments").colorize;

try {
  highlight('puts "Hello World"', 'ruby', 'console', console.log);
}
catch (error) {
  console.error("Error thrown by pygments");
}

Error:
events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: spawn pygmentize ENOENT
    at exports._errnoException (util.js:1020:11)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:193:32)
    at onErrorNT (internal/child_process.js:367:16)
    at _combinedTickCallback (internal/process/next_tick.js:80:11)
    at process._tickCallback (internal/process/next_tick.js:104:9)
    at Module.runMain (module.js:606:11)
    at run (bootstrap_node.js:389:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:504:3

Can you please help me here.

[pksunkara]

You need to have the pygments tool installed along with this library.