A day in the life of...

I've been writing an app for the compact framework for some months now. It's quite a complicated app that includes an object persistence framework, a task oriented application layer and a loosely coupled GUI which is generated through factories (the app only has 1 form, but lots of user controls + factories). The app has been experiencing apparently random OutOfMemoryExceptions, no matter how hard I have tried I have found it impossible to reproduce one of these errors. I have spent quite some time really optimising the memory useage of my OPF so that it works on the bare minimum of memory yet still operates quickly enough (and I'm very pleased with its performance too). However, the OOM exceptions persisted! I wrote a logging tool which records the last X actions the user performs, when an unexpected exception occurs this log is written to disk along with a stack trace of the exception. I noticed that the top of the stack trace always read... at Microsoft.AGL.Com

This is just a copy/paste of a reply I made in a newsgroup, but I think it is quite informative so here it is.... KEY Square brackets denote a class [Person] Rounded brackets denote a role (Pets) Let's say you have a Car class and a Garage class, an individual car is regularly serviced at a specific garage so you have the following association [Garage] (Garage) 1----0..* (ServicableCars) [Car] Car.allInstances->select(Garage.Code = '1234') The above OCL will fail because "Garage" is a class so the parser is expecting stuff like "allInstances". So you might think this should work Car.allInstances->select(self.Garage.Code = '1234') but it doesn't because "self" refers to the root object and not the object at the parsed node where it is specified. This is what aliases are for: {aliasname} + {pipe} Car.allInstances->select(currentCar | currentCar.Garage.Code = '1234') This was possible in Bold too (native wind

I've been reliving my childhood and playing with WinVice, a Commodore 64 emulator. A friend and I were working on a game at the point the C64 died and it never got finished. We recently dusted off those old 5 1/4" disks and finally worked out how to get it working again! If anyone fancies taking a look you can find it here http://noname.c64.org/csdb/release/?id=33963 Be warned though, it really was unfinished. Some rooms lead to dead-ends and there is no way to quit the game, so the occasional reset (of the C64) + reload is required!

Take a look at the following code if (myWeakReference.IsAlive) (myWeakReference.Target as SomeClass).DoSomething(); Do you see the mistake? The WeakReference may return "true" for IsAlive, but because the garbage collector runs within its own thread the value may actually get collected before the next line (because WeakReference.Target does not prevent the GC from collecting the value). I've been using WeakReferences quite a lot recently so I was happy to see that the following changes fixed the occasional NullReferenceException occurencies I had been seeing which were quite difficult to track down! SomeClass myInstance = (SomeClass)myWeakReference.Target; if (myInstance != null) myInstance.DoSomething(); The IsAlive property in my opinion is utterly useless (it is the same implementation as Target). I think MS should just remove it, you could say it would break existing code, but I say it would force people to fix it!

I have a new job. Well, I say "new" but I actually started in December 2005. Anyway, this "new" job requires me to develop compact framework apps. Seeing as Delphi doesn't support CF I am developing my application in VS2005, it's a really nice tool but I miss ECO so much! One thing I had to do was to write an XML importer routine. This would retrieve an XML file detailing tasks due for the next seven days and then import it into the PPC's database. Because I am not responsible for generating the XML, and because it is good practise anyway, I decided to create an XSD file to validate the XML. PDA's have very little storage resources (the flash card is shared between disk and memory) so I decided to read the XML file a line at a time using the XmlReader so that the contents don't exist on the flash memory twice (disk + memory), another benefit of this approach being that I can read it directly from a ZIP file too! In dotnet V2 the class XmlVa

What is a Customer? If you are some kind of business service provider then it will be a Company, if you are a window cleaner then it will be a Person, but if you are a travel agent it could be either. What about a Supplier? You could argue the same as for a Customer, but you could also argue that a Company/Person could be both a Supplier and a Customer. This is where Roles come in. A Supplier isn't something you are, it is something you do, you supply something; just as a Customer consumes something. I find that it is much better to enable "Things" to perform more than one action, it is rare that life is simple enough for everyone to perform only a single role in life. The typical solution to this is the Party/Role pattern. A good point to make here is that this is a pattern, not a set of classes intend for inheriting from! This means that when you have a Company (alias "Party") you should create a CompanyRole class and associate them, descending Custome

I spent the day (March 2005) training someone how ECO works. Between 9:30 and 12:30 we went through the basics, how to create a model in a package (and why). We then covered the different component types, whilst making a simple client/server app. Between 13:45 and 17:00 we went on to Create a server application Convert the client to connect to the server instead of directly to the DB Make the client synchronise with the changes from the server Create a web service which connected to the server for persistence Create a website which connected to the server for persistence That's a lot of work to get done in 3.5 hours at the best of times, but when you are also explaining why everything is done the way it is then this is surely a reflection of just how quick it is to develop applications using ECO. Everything we did was adhoc. I had no idea what the trainee wanted to cover before he arrived so everything was written from scratch. I'm quite frankly surprised that we managed to