Can I identify which form has changed the ownership of a particular component?
For example, I have a
Data Module with a ZTable that is accessed by several forms in the onClose events of those forms , I would need to check if my zTable was opened in form itself. If it was, I close the zTable , if it was not, I do not close.
The best way to do this (for me I do not know if there is an existing pattern) is to create a Helper for the zTable object.
A helper is a Delphi class helper that you can use to add more functionality to a class, without necessarily changing its structure, or making a class derived from it. That is, you will be able to continue using the component directly from the Delphi component palette.
TTableHelper = class helper for TzTable
public
function OpenFromForm: boolean;
function CloseFromForm: boolean;
IsFormOpened: boolean;
IsFormClosed: boolean;
end;
function TTableHelper.CloseFromForm: boolean;
begin
try
Self.Active := False;
Result := True;
ISFormClosed := True;
except
Result := False;
end;
end;
function TTableHelper.OpenFromForm: boolean;
begin
try
Self.Active := True;
Result := True;
ISFormOpened := True;
except
Result := False;
end;
end;
Do the following:
Unit ; uses clause of each Form and Data Module to use; table.OpenFromForm ; table.CloseFromForm ; No Data Module use:
if table.IsFormOpened then
begin
table.isFormOpened := False;
table.Close;
end;