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Intro to Generic Collections with Delphi 2009

A very short introduction to Generic Collections in Delphi 2009. Create a TList of Integers and show adding and removing items from it. Showing some of the differences in types, gotchas and errors you might get.

Generics, or parametrized types, are a type that works with another type that is defined later. Collections are a great example of using them. You create a generic TList, and then when you use it you declare what type it will contain. Then it will be strongly typed to that specific type, both in adding items and removing them.

Delphi Generics work with all types in Delphi: native types (Integer, string, etc.), Records, Objects and Interfaces.

This is screen cast episode 2, shot with Camtasia and hosted on Vimeo.  I had to shoot it at 1280×720 so they will offer it in HD and not downscale it.  Let me know how it works for everyone.

As was pointed out in the comments, the download link only works after you sign into Vimeo.  If that doesn’t work for people let me know and I will come up with a different solution.

10 replies on “Intro to Generic Collections with Delphi 2009”

Great podcast… but leaves me wanting to know if you create a generic list of TObjects, and call the sort method, what magic allows them to sort? 🙂

When you are sorting a “non-standard” type then you provide an IComparer via the overloaded constructor:

constructor Create(const AComparer: IComparer); overload;

Maybe I will demo that later.

Great video, thanks. I was looking for info about Generics, this is great!

wow. what a great video. a great function. i’ve spent hours creating descendants of tlists for integers and other types.

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