[fpc-pascal] Compiler treatment of dotted reference in class property

[Sven Barth]

Howard Page-Clark via fpc-pascal <fpc-pascal at lists.freepascal.org> schrieb
am Mo., 3. Feb. 2020, 11:22:

> FPC 3.0.4 compiles this code excerpt without a murmur:
>
> == code ==
>
> {$mode objfpc}{$H+}
>
> type
>
>    TSheetInfo = record
>      name: String;
>      tab: String;
>      title: String;
>      kind: TSheetKind; // an enumeration
>      color: TColor;
>    end;
>
>    TBaseSheet = class(TTabSheet)
>    protected
>      FSheetInfo:      TSheetInfo;
>      ...
>    public
>      constructor Create(aComponent: TComponent; aSheetInfo: TSheetInfo);
> virtual; reintroduce;
>      ...
>      property SheetKind: TSheetKind read FSheetInfo.kind;  // <<
>    end;
>
>    TEntryGrid = class(TCustomStringGrid)
>    private
>      FParentSheet: TBaseSheet;
>      ...
>    public
>      constructor Create(AOwner: TComponent; aParentSheet: TBaseSheet);
> reintroduce;
>      ...
>      property SheetKind: TSheetKind read FParentSheet.FSheetInfo.kind; //
> <<
>    end;
>
> == code end ==
>
> However, more recent FPCs (and trunk) reject this at the properties
> (marked above <<) with the error "Record or object type expected".
>
> Is there a modeswitch or other wheeze that will get recent FPCs to
> accept dotted notation when specifying property read and write fields?
>

This is simply not allowed for class fields. That it was, was essentially a
bug (
https://wiki.freepascal.org/User_Changes_Trunk#Property_field_access_lists_no_longer_allows_classes
).
Either use records or (TP style) objects or use a getter. If you declare it
as "inline" you can essentially get the same code (with the added bonus
that you can raise an exception should the field be Nil).

Regards,
Sven

>
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