[Solved] How important is it to use “sender”
lazarus / 61-Beginners

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Kraig · 2023-11-20 12:29

I often get warnings that “sender was not used”.
I’m doing fairly simple  things where the sender is the control
itself. To use the sender:tobject  I would have to do type checking
and Type casting. It seems like a lot of extra effort.
I can understand the idea of using sender if more than one type of
control was being sent to the procedure which would cause different
things to happen. Am I being too lazy by not using sender? What’s the
worst thing that can happen?

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Zvoni · 2023-11-20 12:33

Quote from: Kraig on November 20, 2023, 01:29:06 pmI often get
warnings that “sender was not used”.
I’m doing fairly simple  things where the sender is the control
itself. To use the sender:tobject  I would have to do type checking
and Type casting. It seems like a lot of extra effort.
I can understand the idea of using sender if more than one type of
control was being sent to the procedure which would cause different
things to happen. Am I being too lazy by not using sender? What’s the
worst thing that can happen?

If you use one Event-Handler for multiple controls, Sender is your
only way to find out, which control fired it.

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Kraig · 2023-11-20 12:37

Yes I sometimes do that and in that case I do check what the sender is
before using it.

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Bart · 2023-11-20 17:10

Quote from: Kraig on November 20, 2023, 01:29:06 pmAm I being too lazy
by not using sender? What’s the worst thing that can happen?

That depends on what you do in the event.
In most cases it's probably irrelevant who/what Sender is.
As others have pointed out, you can assing 1 eventhandler to multiple
components, and in such a case it may very well be relevant who the
sender is.
Only you, the programmer, knows if this is the case.

Bart

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Kraig · 2023-11-21 00:13

Thanks for the answers