How to identify which form has changed the property of a component?

Question

It is possible for me to identify which form has changed the property of a particular component?

For example, I have a Data Module with a ZTable which is accessed by several forms at the events onClose of those forms, would need to check if my zTable was opened on itself form. If it is, I close the zTable, if it wasn’t, I don’t close.

Answer 1

The best way to do this (for me who 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 altering 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:

1. Create a new Unit;
2. Put this Unit in the clause uses of each Form and of Data Module what to use;
3. When opening the table from the form, use table.OpenFromForm;
4. When closing the table by form, use table.CloseFromForm;

In the Data Module use:

if table.IsFormOpened then
begin
  table.isFormOpened := False;
  table.Close;
end;