Meld Aspects

aspects.js

var when = require('when');
var meld = require('meld');
var winston = require('winston');
var config = require('./config');
 
var dbAspects = {
  introDeferred: function(obj,name) {
    meld.around(obj, name, function(joinpoint) {
      var def = when.defer();
      var promise = def.promise;
      var client = joinpoint.args[0];
      client.query('BEGIN');
      promise.then(function() {
        client.query('COMMIT');
      }, function() {
        client.query('ROLLBACK');
      });
      promise.always(client.release);
      joinpoint.args.unshift(def);
      joinpoint.proceed();
      return promise;
    });
  },
 
  introRollbackDeferred: function(obj,name) {
    meld.around(obj, name, function(joinpoint) {
      var def = when.defer();
      var promise = def.promise;
      var client = joinpoint.args[0];
      client.query('BEGIN');
      promise.always(function() {
        client.query('ROLLBACK');
        client.release();
      });
      joinpoint.args.unshift(def);
      joinpoint.proceed();
      return promise;
    });
  },
 
  introduceDeferred: function(obj, name) {
    meld.around(obj, name, function(joinpoint) {
      var def = when.defer();
      var promise = def.promise;
      joinpoint.args.push(function(err, result) {
        if(err) {
          def.reject(err);
        } else {
          def.resolve(result);
        }
      });
      joinpoint.proceed();
      return promise;
    });
  }
 
};
 
 
var ke$ha = {
  tikTok: function(tag, obj, name) {
    meld.around(obj, name, function(joinpoint) {
      var start, result;
      if(!config.tikTok) {
        joinpoint.proceed();
      } else {
        start = new Date.getTime();
        result = null;
        joinpoint.proceed();
        if(start) {
          result = new Date.getTime() - start;
          winston.log(tag+' '+result);
        }
      }
    });
  }
};

These are great--simple, but effective.

Only one suggestion: it's probably better not to modify joinpoint.args directly. You can pass new args to either joinpoint.proceed() or joinpoint.proceedApply(). For example, instead of:

joinpoint.args.unshift(def);
joinpoint.proceed();

you can do:

joinpoint.proceedApply([def].concat(joinpoint.args));

Now you have me wondering about whether modifying joinpoint.args directly would ever cause a problem :) I better go check teh codez!