Array of TObjectList?

VCL
1

In my XE application, I have a class that among other things, has 2 object lists of the same type. When I access them I do so like this: Object.List1[i].blah or Object.List2[i].blah

For some operations, it would be nice to be able to use Object.Lists[x][i].blah where x selects the list I need to work with. It would also allow more object lists to be added in the future with a lot less effort.

Is there any potential issues with creating an array of TObjectList ? I’ve just tried it and it seems to work, but had second thoughts about using another object list to hold them instead.

2

For that sort of situation, I just use a TObjectList<> to store the object lists - in some cases, I’ve then got a third level TObjectList to effectively have a 3 dimensional array.

I prefer to use TObjectList over a TArray as you can just call free on the top level object list and everything under it including the lower level Obect Lists are all destroyed as well.

3

Yeah, I already have object lists containing other object lists so I guess it’s no different for this really. The creation and freeing is different between object lists and arrays but no real advantage to using an array.

4

Just playing with this again.

Can the index of a TObjectList be accessed as an enum instead of an integer?

ObjectList[EnumValue].SomeProperty := x;

5

Try

ObjectList[ord(EnumValue)].SomeProperty := x;

6

Yeah, that would work, but it’s referred to in a shed load of places so I was wanting to avoid the casts everywhere.

7

Hi David

Without seeing your code it may be possible to declare a function that takes the enum parameter or use a helper to your TObjectList.
You may need to do some sort of global replace.

Regards
Graeme

8

You may be able to use a TObjectDictionary instead of an Object list.

9

I keep meaning to have a look at TDictionary, etc.