Archives

Archives / 2008 / June
  • Email form disabled again...

    I've again disabled the email form on this blog, because I now get about 15 spam emails every 5 minutes through this form and enough is enough. Apparently it's not fixable by the blog-engine overloads, so this is the only option. If you want to contact me, my email address is on the about page.

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  • Linq to LLBLGen Pro: feature highlights, part 1

    Some people asked me what the highlights are of Linq to LLBLGen Pro, which was released this week, as it seems that Linq support is apparently growing on trees these days. In this and some future posts I'll try to sum up some of the characteristic features of Linq to LLBLGen Pro, so you don't have to wade through the 15 articles I wrote about writing Linq to LLBLGen Pro . I'll write several of these articles, this is the first one. I hope to write more of them in the coming weeks.

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  • LLBLGen Pro v2.6 has been released!

    After almost 11 months of design, development, beta testing and adding final polish, it's here: LLBLGen Pro v2.6! This version, which is a free upgrade for all our v2.x customers, has a couple of major new features, the biggest of course being the full implementation of Linq support in our O/R mapper framework. The work on our Linq provider, which we've dubbed 'Linq to LLBLGen Pro', lasted almost 9 months and was discussed on this blog in a series of articles, which I'll linq () to below.

    In the beginning of writing the Linq provider, I was pretty optimistic that it would be easy and quick, but after a while I got very pessimistic and wanted to skip it entirely as it would simply cost too much effort, and therefore time and money. The main reason was the lack of serious documentation and background on various essential details like which expression trees were formed from which linq queries, and how to understand them in full so a meaningful query could be produced from them to run on the database. Anyone who has written some form of Linq provider or is currently busy doing so will run into this problem. Doing trial-error development/research for a couple of months in a row isn't a picknick, but it's also part of being a Software Engineer so it always left me with a mixed bag of what to think of it: it's exciting and interesting, but also frustrating.

    A good example of the lack of serious documentation on expression trees is the way the VB.NET compiler compiles a group-by query into an expression tree vs. how the C# compiler does that: the C# compiler always adds a separate .Select() method call, the VB.NET compiler doesn't. In theory, the VB.NET compiler is right: the group-by clause has to be in the same query scope as the projection, but as C# has to be supported as well, you have to build some form of 'look-ahead' inside the tree to see when / if / how the projection is present after the group-by expression is seen. This isn't documented anywhere. Another one is the way how anonymous types are detected. There's no boolean on the Type object which tells you 'This is an anonymous type'. So you check the name. The C# compiler generates names which start with <>, the VB.NET compiler generates names which start with $VB$. And probably yet another language which runs on the CLR and which adds Linq support might choose another prefix. Nowhere is this documented but it is sometimes required to know that the type you're dealing with is an anonymous type.

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