As part of an attempt at multi-threading, I have had to move
many things that used to be global into the Implementation
parts of units in order to enforce privacy. When I moved a
routine passed as a parameter and put it inside the routine
to be threaded, the program ceased to work. I append the
essential code abstracted from my program:
Program Test ;
Uses TestSub ;
Begin
Test_it ;
End.
Unit TestSub ;
Interface
Procedure Test_it ;
Implementation
Const
Chunksize = 24 ;
Arraysize = 100 ;
Type
ProcT = Procedure(Const P1, P2 : Pointer) ;
BArray = Array[0..1999999999] Of Byte ;
Chunk = Array[0..Chunksize-1] Of Byte ;
Var
Data : Array[0..Arraysize-1] Of Chunk ;
Procedure Do_it(Var A ; Const N, NB : Longint ; F : ProcT) ;
Begin
Writeln('Do_it: expect'#9, Longint(@A), #9, Longint(@Barray(A)[NB])) ;
F(@BArray(A)[0], @BArray(A)[NB]) ;
End ; { Do_it }
Procedure PrPublic(Const f1, f2 : Pointer) ; { Visible }
Begin
Writeln('PrPublic'#9, Longint(f1), #9, Longint(f2)) ;
End ; { PrPublic }
Procedure Test_it ;
Procedure PrPrivate(Const f1, f2 : Pointer) ; { Private }
Begin
Writeln('PrPrivate'#9, Longint(f1), #9, Longint(f2)) ;
End ; { PrPrivate }
Begin { Test_it }
Do_it(Data, Arraysize, Chunksize, @PrPublic) ;
Do_it(Data, Arraysize, Chunksize, @PrPrivate) ;
End ; { Test_it }
End.
Output:
Running "c:\fpc\2.4.2\exe\test.exe "
Do_it: expect 4252848 4252872
PrPublic 4252848 4252872
Do_it: expect 4252848`4252872
PrPrivate 4252872 4234688
When the routine being passed as a parameter is in the top level
of the unit, "PrPublic", all is well; the expected pointers are
passed. When an identical routine "PrPrivate" is hidden inside
the top level routine "Test_it", the expected 2nd pointer appears
in place of the first and an apparently random pointer appears
second.
What am I doing wrong?
Andrew Bennett
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