On 24.03.2018 23:33, Ondrej Pokorny wrote:
Another question about this sentence in FPC docs: "Managed types are
always initialized: in general this means setting the reference
count to
zero, or setting the pointer value of the type to Nil."
Does it mean I can assume a local string variable is always
(=whenever
the routine is called) initialized to ''? I.e. that TestB always
returns
'a'?
For managed types this is indeed guaranteed. Otherwise there'd be
exceptions upon the first use of the variable as the RTL would assume
that the value is valid.
OK, thanks. My assumption was that setting local managed types to nil
is guaranteed only once at the first routine call. And that it is an
implementation detail if it is niled at the second call or reused from
the first call.
I probably mixed it up with the Result variable (what Maciej wrote about).
I found the source of my assumption, I get a compiler warning in this case:
program StringsTest;
function Test: string;
var S: string;
begin
S := S + 'a';
Result := S;
end;
begin
Writeln(Test);
end.
Emits:
StringsTest.lpr(5,8) Warning: Local variable "S" of a managed type does
not seem to be initialized
Why do I get the compiler warning when the variable is indeed guaranteed
to be initialized to nil/empty string?
Ondrej
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
