Container to store anonymous methods

Question

I have a following definition.

type
  TOmniTaskDelegate = reference to procedure(const task: IOmniTask);

What type of container should I use (should be supported in D2009) to store a list of TOmniTaskDelegate instances? Currently I'm using array of TOmniTaskDelegate but I'm not really happy with that.

Answer 1

I would use TList<TOmniTaskDelegate>. Since this is typesafe due to the use of generics, it will correctly handle the lifetime issues of its members.

Answer 2

Edit: Delphi 2009 includes the generic TList<T>, I assume it's implemented using array of, just as the one in Delphi 2010. That makes the TList<T> the optimal choice! My original answer stays because it explains why array of is a great data structure and why not using it is a lot of trouble.

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Your choice of array of Anonym looks very good to me because:

• Anonymous methods are managed entities (implemented using interfaces). They need to be properly finalized.
• The dynamic array is itself a managed type, making sure the anonymous method references are properly finalized.
• Delphi 2010 generic containers are implemented using dynamic arrays, so they're up to the task. But make sure you don't grow your arrays one-by-one, grow in chunks.

If you use anything else for the implementation you'll need to take care of finalizing the references yourself. Examples:

• If you use plain blocks of memory you'll need an destructor that deliberately sets each item to nil (ie: not ZeroMemory or FillChar) so the compiler gets a chance to generate finalization code.
• Records are managed objects, and they could hold references to dynamic methods, but they can only hold a finite number of references, if you need more you'll need to implement a sort of linked list and then you'll need to carefully manage there life cycle.
• Classes suffer all the deficiencies of records, and they add their own layer of overhead on top of that.