[fpc-pascal] Open vs dynamic arrays

Mark Morgan Lloyd markMLl.fpc-pascal at telemetry.co.uk
Sun Apr 22 12:04:28 CEST 2012

cobines wrote:
> 2012/4/22 Mark Morgan Lloyd <markMLl.fpc-pascal at telemetry.co.uk>:
>>  but I'm not sure why that works when it
>> didn't earlier (i.e. before I'd started using array of const).
> You said you used
> DbgArray= array of integer
> then I assume this declaration?
> procedure ClrDebug(const panels: DbgArray);
> If so the parameter is a dynamic array not open array and you cannot
> call it with constant array:
> var
>   arr: DbgArray;
> begin
>  ClrDebug([DbgKey, DbgCode1, DbgTx]); //Won't work
>  SetLength(arr, ...);
>  arr[0] := ...
>  ...
>  ClrDebug(arr);// This works
> end;
> This on the other hand is an open array parameter:
> procedure ClrDebug(const panels: array of integer);

Thanks, succinct. So if I understand this correctly it's one of the very 
rare cases where one has to write out the type of a parameter in full, 
rather than using an earlier declaration.

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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