[fpc-devel] GetPropValue and enumerated types (Bug #4738 follow-up)

[Graeme Geldenhuys]

Thanks Michael.  I'll have a look at RTTIUtils now,

Graeme.



On 17/05/06, Michael Van Canneyt <michael at freepascal.org> wrote:
>
>
> On Wed, 17 May 2006, Graeme Geldenhuys wrote:
>
> >> Even so:
> >> > This Assign() method does not need to use a variant, but can still offer
> >> > the same functionality as it does now. It just means that the method
> >> > needs to determine the actual type itself...
> >>
> >> tiOPF has done a lot to get rid of using variants and it isn't used
> >> that much anymore.  If there is anything else we can do to get rid of
> >> the last few cases, we would.
> >> Below is one of the methods used in the Assign method.  GetPropValue
> >> and SetPropValue returns/uses Variant, so how would you do it
> >> otherwise using RTTI?
> >> eg: Query PropInfo and call the individual methods (GetOrdProp,
> >> GetStrProp, etc.) based on PropInfo.Kind in a case statement?
> >>
> >> const
> >>   // All string type properties
> >>   ctkString = [ tkChar, tkString, tkWChar, tkLString, tkWString
> >>                         {$IFDEF FPC},tkAString{$ENDIF} ] ;
> >>   // Integer type properties
> >>   ctkInt    = [ tkInteger, tkInt64 ] ;
> >>   // Float type properties
> >>   ctkFloat  = [ tkFloat ] ;
> >>   // Numeric type properties
> >>   ctkNumeric = [tkInteger, tkInt64, tkFloat];
> >>   // All simple types (string, int, float)
> >>   ctkSimple = ctkString + ctkInt + ctkFloat ;
> >>
> >> procedure TtiObject.AssignPublishedProp( pSource : TtiObject ;
> >> psPropName : string) ;
> >> var
> >>   lPropType: TTypeKind;
> >>   lPropValue: Variant;
> >> begin
> >>   lPropType := TypInfo.PropType( pSource, psPropName ) ;
> >>   if lPropType in ctkSimple + [tkVariant, tkEnumeration] then
> >>   begin
> >>     { Graeme 2006-05-16: Passing in False, as a workaround for a FPC bug. }
>
> Change your code to something like
>
>         Case lproptype of
>           tkInteger : SetIntProp(Self,psPropName,GetIntProp(psource,pspropname));
>           tkString  : SetStrProp(Self,psPropName,GetStrProp(psource,pspropname));
>           // And so on. See e.g. RTTIUtils for a more complete list.
>        else
>          Raise Exception.Create(UnSupportedRTTIType)
>        end;
>                       ;
> >> > Variants are for (excuse me the term) lazy coders...
> >>
> >> I've heard that before.. :-)
>
> It must be true then :-)
>
> Michael.
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>


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