On Tue, 24 Oct 2017, Giuliano Colla via Lazarus wrote:
Il 23/10/2017 22:57, Mattias Gaertner via Lazarus ha scritto:
Check if 'Self' inside SendMessage is the right instance.
The moral of the story is: in Delphi mode you can assign a procedure of
object to a pointer, and the compiler doesn't complain, but it is wrong,
because when you call your method through this pointer, the method is
executed, but it's unaware of the data space of the object it belongs
to, even if it's called from another method of the same object! If the
method doesn't access variables of the object, everything appears to
work, but if it does the program simply crashes.
I will try to see if the same occurs also in Delphi, to understand if
it's a Delphi bug or an fpc bug.
A valid method can never be stored in a pointer, since the former is actually
2 pointers (method/data) and the latter is just 1 pointer.
That the assignment is valid is Delphi compatible: only the procedure
address is copied.
Michael.
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