Overriding/hiding inherited published properties
I am making a component that is a descendent of TDrawGrid.
Lets say that I want these properties (among others) to be published: Width, Height, ColCount, RowCount.
When the user changes one of these, I want the methods found in DrawGrid to take care of it. However, before this is done, I need my component to take care of some other things, such as memory allocation.
For example, say that the user increases RowCount by 1. I need to allocate additional memory and do some other things (for the purpose of my component), and then let TDrawGrid do whatever is needed to change the rows.
How would I hide the inherited properties, and include new properties of the same name that call the inherited properties? I think I should use the "inherited" keyword, but I am not exactly sure.
Another, similar question:
How would I hide (i.e. make private to my component) any inherited published properties, yet still make them available to my component?
For example, lets say I wanted to make Height and Width (in DrawGrid) totally unavailable to the user and other components, but I want to retain them for private use by my component. How would I do that?
If it matters, I am using Delphi 2.
Lets say that I want these properties (among others) to be published: Width, Height, ColCount, RowCount.
When the user changes one of these, I want the methods found in DrawGrid to take care of it. However, before this is done, I need my component to take care of some other things, such as memory allocation.
For example, say that the user increases RowCount by 1. I need to allocate additional memory and do some other things (for the purpose of my component), and then let TDrawGrid do whatever is needed to change the rows.
How would I hide the inherited properties, and include new properties of the same name that call the inherited properties? I think I should use the "inherited" keyword, but I am not exactly sure.
Another, similar question:
How would I hide (i.e. make private to my component) any inherited published properties, yet still make them available to my component?
For example, lets say I wanted to make Height and Width (in DrawGrid) totally unavailable to the user and other components, but I want to retain them for private use by my component. How would I do that?
If it matters, I am using Delphi 2.
ASKER CERTIFIED SOLUTION
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Of course you should change (TEdit) to (TDrawGrid)... :-)
ASKER
OK. Thanks. Just a couple of things I need clarified.
1. If I DID want to make the Width property (the new property for my component, as shown in your code) visible to others, I just simply move it from private to public or published, right?
2. Let's say I wanted to totally hide FixedRows and not do anything with it. All I want to do is keep the user from changing it. Do I simply exclude it from my property definitions, or is there more to it?
1. If I DID want to make the Width property (the new property for my component, as shown in your code) visible to others, I just simply move it from private to public or published, right?
2. Let's say I wanted to totally hide FixedRows and not do anything with it. All I want to do is keep the user from changing it. Do I simply exclude it from my property definitions, or is there more to it?
ASKER
Adjusted points to 65
(1) That's right... :-)
(2) Hmmm. If you derive your component from TDrawGrid then your component will have all properties published, that TDrawGrid published, too. That means you have to DO something in order to hide such a property.
You could try just this:
private
FixedRows;
public
Perhaps that's all. I'm not sure about that. If it doesn't work, then use the same stuff as I showed you with the Width property, but just leave your GetFixedRows/SetFixedRows functions empty.
Regards, Madshi.
(2) Hmmm. If you derive your component from TDrawGrid then your component will have all properties published, that TDrawGrid published, too. That means you have to DO something in order to hide such a property.
You could try just this:
private
FixedRows;
public
Perhaps that's all. I'm not sure about that. If it doesn't work, then use the same stuff as I showed you with the Width property, but just leave your GetFixedRows/SetFixedRows functions empty.
Regards, Madshi.
ASKER
Thanks.