Goto
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goto is an unconditional jump to a previously declared label (either before or after the goto command).
It is a reserved word.
Usage of goto in high-level programming languages such as Pascal is highly discredited, since control structures of all sorts are available.
The last situation a goto is agreed with bad grace to be a significant system error, where a “graceful exit” is better than causing a system breakdown.
As an example, here an excerpt from FPC’s code base rtl/inc/extres.inc]:
procedure InitResources;
label ExitErrMem, ExitErrFile, ExitNoErr;
begin
ResHeader:=GetMem(sizeof(TExtHeader));
if ResHeader=nil then goto ExitErrFile;
goto ExitNoErr;
ExitErrMem:
FreeMem(ResHeader);
ResHeader:=nil;
ExitErrFile:
{$I-}
Close(fd);
{$I+}
ExitNoErr:
end;
According to the value of returnNilIfGrowHeapFails getMem possibly may return nil.
Instead of placing everything in a “success”-branch, a couple goto instructions were chosen.
