ernestly?

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[ernestly-blog]

Javascript and inheritance, gotcha...

I ran into one little issue when using the built in inheritance helper from node.

I created a "class" with some methods, this class should inherit from EventEmitter. Naturally I did this:

var util = require('util'); var EventEmitter = require('events').EventEmitter; function myClass() { EventEmitter.call(this); } myClass.prototype.mySetter = function() {}; util.inherits(myClass, EventEmitter);

When I was using an instance of this very class, the setter function was gone. This was very odd and it took me quite a time until I realized that the inherits helper overwrites the prototype of my ChildClass. (Which became obvious when I was looking at the source: https://github.com/joyent/node/blob/master/lib/util.js#L557 )

So, the right way to do the inheritance was simply moving the inherits line up: 

var util = require('util'); var EventEmitter = require('events').EventEmitter; function myClass() { EventEmitter.call(this); } util.inherits(myClass, EventEmitter); myClass.prototype.mySetter = function() {};

That's it....

[ernestly-blog]

Obviously Github has some kind of time machine tuning issues. When I posted a comment beneath a gist, they told me my comment will be written "In a few seconds".

Good job Github!

[ernestly-blog]

Running XAMPP under Windows

I just installed XAMPP on my computer when trying to start the apache I ran into two problems:

Skype was running and was bound to port 80 so that Apache could not use that one. One possibility is to change the standard port in the httpd.conf of Apache. Another possiblity is to switch of the usage of port 80 and 443 (SSL) in Skype, there's a special checkbox for that.

After hat when trying to start the Apache service I got the error message "Error: Apache shutdown unexpectedly.". One posting somewhere in a message board suggested to deactivate the SSL module if it is not used:

#LoadModule ssl_module modules/mod_ssl.so

After doing so the apache service ran fine.

[ernestly-blog]

NPM is just cute :)

I was just fiddling around with npm (the package manager for node.js) and was calling the help section with entering

[sanchez] ~$ npm -h

As assumed I got the following output: (shortened)

Usage: npm <command> where <command> is one of: add-user, adduser, apihelp, author, bin, bugs, c, cache, completion, config, ddp, dedupe, deprecate, docs, edit, explore, faq, find, find-dupes, get, help, help-search, home, i, info, init, install, isntall, la, link, list, ll, ln, login, ls, outdated, owner, pack, prefix, prune, publish, r, rb, rebuild, remove, restart, rm, root, run-script, s, se, search, set, show, shrinkwrap, star, start, stop, submodule, tag, test, tst, un, uninstall, unlink, unpublish, unstar, up, update, version, view, whoami

I scanned over the list of possible commands and then one special command catched my eye:

isntall

I looked the source up on Github and realised that 'npm isntall' is just an alias for 'npm install'. npm is just cute and helping the user out with this nasty kind of error one does over and over again... :)

[ernestly-blog]

PHP, modulus and floating point numbers (srsly?)

On a nice sunny and quite warm september afternoon I decided I'll do the unspeakable and try to calculate the modulus of a float value. This is easy as pie, so I wrote

[sanchez] ~$ php -r "echo 0.1 % 1;"

What I expected was of course:

0.1

What I got was:

0

PHP, seriously? You're implicitly assuming integers, thus casting the numbers to integer and spit out just a simple and plain 0? PHP, we spent a very long time together and I mostly enjoyed it but I think you have to leave soon...

If you want the expected behaviour one has to use 'fmod':

[sanchez] ~$ php -r "echo fmod(0.1,1);"

In addition I asked my self: WWJSD (what would JavaScript do):

[sanchez] ~$ node > 0.1 % 1 0.1

WWPYD (what would Python do):

[sanchez] ~$ python Python 2.7.3 (default, Aug 1 2012, 05:14:39) >>> 0.1 % 1 0.1

So once again: PHP, srsly?

[ernestly-blog]

On Google and false assumptions on search phrases

In the past few month I ran into that problem that the search results I get when searching for a specific phrase are getting really bad. Google makes an assumption about which of the submitted keywords "really" matter for the result of the search operation and in my experience here they fail more and more often.

My favorite example into which I ran just yesterday goes like this: I had problems with my package database on my ubuntu system as it got corrupted during the 12.04 update. So I was searching for "system database (apt)". (I did not use quotes to combine the words to an exact match as I wanted a broader result)

What I got was this:

Notice that I am located in *germany* using the *german* google page! (http://www.google.de) In which universe could I be interested in apartments in Houston and Dallas when I was searching for "system database (apt)"? Sure "apt" is the short form of apartment, but why did Google decide to completely omit the phrases "system" and "database"?

And why is this search result entry located on #2?

Perhaps some real estate agent in Houston paid a fair amount of money to a certain adress located in mountain view?

Things like this happend to me not only once and in my opinion it is getting worse. I'd say 10 years ago google did a better job than this.

[ernestly-blog]

PHP DateTime format and DateInterval format

I will never understand the inconsistency in PHP's API.

Why do I have to use the percent when formatting the output of a DateInterval object, but I don't have to use the percent when formatting the output of a DateTime object!

$dt = new DateTime();  $di = new DateInterval( "PT1H" ); echo $dt->format( '%H:%i:%s' ); echo $di->format( 'H:i:s' );

For the future I really like to stick more to node.js as JavaScript Style of doing things is far more pleasant and convenient...

[ernestly-blog]

Thoughts an synchronous/asynchronous behaviour in node.js

A thing that bothers me for a while now are the expections someone who invokes a (said to be) asynchrounos JavaScript function has.

Let's assume there's a function that accepts a callback that receives the return value of the executed function:

function myFunction( callback ) { //do something callback( something ); }

Now someone invokes this function:

myFunction( function( something ) { console.log( 'a' ); } ); console.log( 'b' );

My point is:

Is it always save for the user (the one that invokes the function) to make an assumption about the order of the events 'a' and 'b'? Resulting: Is it considered bad coding style to rely on the exact behaviour? (Not talking about the runnig time but about synchronicity or asynchronicity!) Someone might think that `myFunction` is asynchronous thus 'b' has to happen _always_ before 'a'.

Here's a little example. Someon wrote the class 'myClass'. He utilizes the method 'someAsynchronousFunction' to do something. As the function calls a callback when ready, the author of 'myClass' makes the assumption of 'true' asynchronicity. He emits the event 'init' when the initialization is completed. Now someone uses the 'myClass'. A new object is instantiated and as the user of 'myClass' knows that 'myClass' emits an init event, he binds an event listener to that specific event. Now: If 'someAsynchrounosFunction' does *not* behave truly asynchrounos, and returns immediatly instead, the event 'init' gets fired when the event handler of 'init' is not bound.

function myClass() { function initialize() { someAsynchrounosFunction( function (err, data) {  this.emit( 'init' ); } ); } initialize(); } var o = new myClass(); o.on( 'init', function() { //will never be fired if someAsynchrounosFunction would behave synchron instead of asynchrounos! } );

The other way around:

As the someone who designs a certain function, is it considered bad coding style to not have a predictable order? Maybe it is necessary to wait for a certain event to happen, resulting in an asynchronous answer, or maybe this exact action has not to be awaited thus asynchronicity is not required.  Would it be the best in this case to add a process.nextTick(...) to always have the same behaviour?

I have a special case where this exact question came to my mind: I worked on some kind of utility (persistentFileDB in my Utility Repo) that provides the Possibility to store Javascript-Objects persistently. It works that way that initially (on server startup) a file (consisting of JSON-objects) get loaded. While the file is loading (asynchrounos of course), no query can be answered. So every query that is made will be defered and stored until the file operation has finished. When this happens all the queries get resolved and the results are returned to the asynchrounos callbacks.

Pretty straight forward.

In the case that the file is already loaded a call to 'getRecord(...,function() {} );' could be resolved instantly, thus no asynchronicity is required.

What would someone who uses this class assume? 

I came to the conclusion that if asynchrounicity is needed at least one time, the function should behave asynchrounous. So even if the work can be done synchrounos one should defer the execution to meet the expectations of the client.

(BTW: check out my EventedQueue in my eventedQueue branch in Async, that's the underlying mechanic that ensures the queueing and invoking of incoming events)

[ernestly-blog]

First pull request on Git Hub got merged :)

At the moment I'm extremely excited, my first two Pull Requests I ever made got merged pulled in the upstream repository!

I've been following the async project which provides a nice flow control library for node.js quite a while a thought it would be nice to have some little extensions.

I made an update to the 'queue' which allows adding tasks in bulks and I submitted a bug fix for several tests that keep crashing with the current version of node.js.

Check out my repo on Github and check out Async on Github in the first place!

[ernestly-blog]

Hanlon's razor

Awesome quote I found on the Interwebz:

Never attribute to malice that which is adequately explained by stupidity.

[ernestly-blog]

Finding good employees is hard

The company I'm working at is currently looking for somone to work at our web development department.

We got a lot of applications, a few goog guys and many real weird ones:

My favorite is the one who claims:

"...by learning several programming languages like Html and CSS it is possible for me to work on a large spectrum of challenges and to fulfill them."

Another one was a constructor of metal planes who likes to work on our website. Well, what about building our own plane? Maybe that could speed up our deliveries to oversea...

The third candidate was an artist (painter), worked as electrician, with cnc machines, than as a painter, technical drawer, studied architecture, worked at a gas station and in fact did also an educational training as an it guy.

[ernestly-blog]

Douglas (RIP)

It is a mistake to think you can solve any major problems just with potatoes. 

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