[Lazarus] Messages unit
patspiper at gmail.com
Tue Apr 26 15:25:55 CEST 2011
Description of Lazarus' Messages unit:
"This unit defines some of the most common definitions of Delphi's
messages.pas to make porting easy. It is not used by the LCL itself."
It is thus used along with the LMessages unit in converted Delphi
projects to eliminate the need to change messages from TWxxx to TLxxx
all over the project. Example:
procedure TWinControlDecsendant.WMPaint(var Message: TWMPaint);
Lazarus Messages unit:
TWMPaint = TLMPaint;
The above is exactly what happens under Linux to make things work
smoothly. However under Windows, FPC's Messages unit takes precedence
and hides Lazarus' Messages unit.
FPC Messages unit:
TWMPaint = Windows.TWMPaint
and the code is broken as PaintHandler expects TLMPaint as an argument
but receives Windows.TWMPaint instead.
I suggest renaming and/or aliasing Lazarus' Messages unit as
WinMessages. Aliasing (2 units using the same include file?) could prove
to be a good solution as it does not disrupt old code.
More information about the Lazarus