Posts

Quantum bugs

I've just been driven mad by a "Quantum bug". What is a quantum bug? Well, it's a bug that doesn't exist unless you look at it :-) I kept getting a NullReferenceException in my code. It happened whenever I changed a property of a class. I assumed it was something in the framework, but it was in fact in a library of my own. When the property changed it would trigger an observer I had attached, the purpose of this observer is to check if the form that owns my component is the active form, if it is then it records the object that changed; the purpose is to know which objects were modified by which form. Anyway, to check if the form is active I do this Form activeForm = System.Windows.Forms.Form.ActiveForm; Form activeMdiChildForm = activeForm.ActiveMdiChild; if (activeForm == this.Form || activeMdiChildForm == this.Form) ..... Now the quantum! If you are debugging your app Form.ActiveForm will always return null! How useful is that eh? :-) So, when debugging

Cocoa, falling at the first hurdle?

I was REALLY looking forward to programming some apps on the Mac using Cocoa and objective-C. I am reading "Cocoa programming for MAC OS X" by Aaron Hillegas. I had read as far as page 30 when I saw the following: "Objective-C is a very simple language. It has no visibility specifiers: All methods are public; and all instance variables are protected. (Actually, there are instance specifiers for instance variables, but they are rarely used. The default is protected, and that works nicely.)" WHAT? Works nicely? I disagree! It is actually possible to make a class's method private by not including it in the interface declaration (myclass.h) and just adding the implementation file instead, but what about protected methods? public I expose as little as needed to ensure the class provides the service it was designed to. The signatures/names of members in my public area change as little as possible so as not to break other people's code. Public members are

Enough rails for me

That's it, I've had enough of Ruby on Rails! I like the rails part, it's a very clever approach, but I really dislike the Ruby part! The final straw occurred yesterday. It's very common in OOP to have the constructor set default values for your object just in case the consumer of your class does not set them. In C# I would do something like this..... public class Post : MyBaseClass { private bool isPost = true; } In Ruby I was trying to achieve this simple behaviour... 01: IsPost is set to true 02: A form is displayed with the default value 03: User changes the value 04: My Post instance is updated with the values from the form I tried to override Initialize() only. def Initialize super is_post = true end Now Post.new(params[:post]) is not reachable for some reason. So in my Post class I did this def Initialize(* params) super(params) is_post = true end The problem here is when I try to initialize the values from the form in my controller class. post = Pos

Installing Rails on a Mac

What a lot of grief! After trying more simple steps on another site (and failing) I eventually managed to get the following steps to work: http://hivelogic.com/narrative/articles/ruby-rails-mongrel-mysql-osx There were however some changes: 01: Make sure you download TextMate. I kept reading it as TextEdit for some reason, so just be aware of that when "mate ~/.bash_login" wont work. 02: One of the steps tells you to type "make ~/.bash_login". I found that adding the suggested text to that file made no difference when you log out/in or close the Terminal window. This was because a file named "~/.bash_profile" existed. If this file exists then you should modify it instead of the one mentioned in the article. 03: When trying to do "rake db:migrate" I would experience the following error: otherwise you will experience the following error: dyld: NSLinkModule() error dyld: Library not loaded: /usr/local/mysql/lib/mysql/libmysqlclient.15.dylib Re

Convert absolute path to relative path

Today I needed to convert an absolute path to a relative path based on a specified base path. E.g. c:\a\b\c -> c:\a\b\c\d\file.txt = d\file.txt c:\a\b\c -> c:\a\file.txt = ..\..\file.txt c:\a\b\c -> c:\a\x\file.txt = ..\..\x\file.txt I am surprised there is nothing in the .NET framework so I had a hunt around and converted the code from the following URL ( http://www.vergentsoftware.com/blogs/ckinsman/default.aspx?date=2006-08-07 ) into C#.... private string RelativePath(string absolutePath, string relativeTo) { string[] absoluteDirectories = absolutePath.Split('\\'); string[] relativeDirectories = relativeTo.Split('\\'); //Get the shortest of the two paths int length = absoluteDirectories.Length < relativeDirectories.Length ? absoluteDirectories.Length : relativeDirectories.Length; //Use to determine where in the loop we exited int lastCommonRoot = -1; int i

Acer Skoda - I mean Ferrari

I have owned an Acer Ferrari now for approximately 13 months. Previously I had a problem with it freezing randomly. I spent some time trying to reproduce the problem and after a month or two was finally able to reproduce it 100% of the time. I sent my laptop back to Acer armed with exact steps and as a result my laptop was returned to me after only a couple of days. For the past 2-3 months I have been seeing very rare, random resets. Obviously I blamed Windows, as you do :-) Some software I had to convert AVI to MPEG would always reset the laptop, but I just put that down to dodgy software. More recently I noticed that 7-zip would also reset my laptop *only* if I used ULTRA compression on a file larger than 500MB. So I tried Winzip, same problem. I installed Vista and tried both Winzip and 7-zip in there, same problem. With steps to reproduce + proof that it was not the OS I felt I could finally send the laptop back for repair without running the risk of it coming back "No

Sprites

Someone sent me this on Skype this morning. I think it's really cool, it reminds me of the hardware sprites on the old Commodore 64! 01: Go to any site with lots of images (image search on google is a good one) 02: Once the images appear copy/paste this text into your address bar. javascript:R=0; x1=.1; y1=.05; x2=.25; y2=.24; x3=1.6; y3=.24; x4=300; y4=200; x5=300; y5=200; DI=document.images; DIL=DI.length; function A(){for(i=0; i<DIL; i++){DIS=DI[ i ].style; DIS.position='absolute'; DIS.left=Math.sin(R*x1+i*x2+x3)*x4+x5; DIS.top=Math.cos(R*y1+i*y2+y3)*y4+y5}R++}setInterval('A()',5 ); void(0);