dispose: bug or feature?

10 Dec 2007

      Hi
Given a pointer p, dispose(p) does not set p to nil.

This program,

program tst;
type
   ptr = ^string;
var
   p : ptr;
begin
   p := new( ptr, 20 );
   p^ := "abc";
   writeln( p^ );
   dispose( p );
   p := nil;
   if p = nil then
     writeln("OK");
   dispose( p );
   writeln( p^ );
end.

as is gives you

abc
OK
segmentation fault

The seg fault is from the last writeln.
If you comment out the line "p := nil", the second "dispose" causes
a core dump.
If you comment out both "p := nil" and the second "dispose" you get

abc
abc

and that's also an error.

I do not know what side effects you might get if you caused "dispose"
to set the pointer to nil.

   Russ

Russell Whitaker

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