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

[Howard Page-Clark via fpc-pascal]

On 03/02/2020 13:17, Sven Barth via fpc-pascal wrote:
Howard Page-Clark via fpc-pascal > 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


Thanks for the reference and clarification.

Howard



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

[Sven Barth via fpc-pascal]

Howard Page-Clark via fpc-pascal  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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[fpc-pascal] Compiler treatment of dotted reference in class property

[Howard Page-Clark via fpc-pascal]

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?




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