Debug: being able to enable/disable debug programmatically

[roccomuso]

Wouldn't be useful to be able to enable and disable debug mode programmatically from node scripts?

debug.enable()
debug.disable()

[roccomuso]

+1

[ernie58]

You can work around it like this:

require('debug').enable('myapp:somenamespace'); //enable namespace
debug = require('debug')('myapp:somenamespace'); //reload debug

[roccomuso]

I don't know if we mean the same thing. Actually I did something like that:

// enable
process.env.DEBUG = '*'; 
var debug = require('debug')('namespace');
debug('printed');

// disable
delete process.env.DEBUG;
var debug = require('debug')('namespace');
debug('not printed');

[ernie58]

It's the same thing!
But I think my solution adds the namespace, while yours replaces it? Don't know for sure...

[roccomuso]

Generally speaking, the debug modules will not work if you do not use a DEBUG envroinment variable. Correct me if I'm wrong.

[pulkitsinghal]

@ernie58 - your workaround was quite useful. I wanted to make sure that any errors I have, will always get logged (let's skip the pros/cons of console.error) even if the namespace isn't turned on explicitly. I'm sharing the function where I wrapped your workaround for use in my code:

/**
 * Creates a debug logger object for a given scope (a.k.a. namespace)
 * and if the level of logging happens to be `error` then programatically
 * enables that namespace.
 *
 * Wanting to always enable errors, led to a minor implementation change
 * such that now log_level (only for error) also gets added to the namespace dynamically.
 *
 * So if DEBUG does not enable `my:namespace` explicitly, even then:
 * > my:namespace:error (will be enabled)
 * ... but `my:namespace` will be left as disabled.
 *
 * @param level
 * @param scope
 * @returns {*}
 */
function createLogger(level, scope){
  /* NOTE: Moved it, in order to create fewer objects.
   *       If left here, then we would end up with separate objects for
   *         > my:namespace:info
   *         > my:namespace:debug
   *         > my:namespace:trace
   *       as well!
   */
  //scope += ':' + level;

  // enable namespace programmatically
  // https://github.com/visionmedia/debug/issues/275
  if (level === 'error') {
    scope += ':' + level;
    console.log('will try to enable namespace:', scope);
    // NOTE: the goal is to enable `my:namespace:error` when DEBUG is not set for `my:namespace`
    //       but this code will run even when `DEBUG=my:namespace` ...
    //       Yet it doesn't seem to cause any problems or conflict so its fine, I suppose.
    require('debug').enable(scope);
  }

  var logger;
  if (scope) {
    logger = debug(scope);
  } else {
    logger = debug;
  }
  return logger;
}

[ernie58]

great!

[thebigredgeek]

https://github.com/visionmedia/debug/issues/370 closing