Inspired by this question (“How to get default value for property using RTTI)
I thought of how to use the information in there to have a routine that could assign default values to all properties of a class on demand.
See my solution in the answer…
<code>USES System.RTTI;
TYPE
TPropertyHelper = CLASS HELPER FOR TRttiProperty
FUNCTION IsOrdinal : BOOLEAN; INLINE;
FUNCTION Default : TValue;
END;
{ TPropertyHelper }
FUNCTION TPropertyHelper.Default : TValue;
VAR
DEF : INTEGER;
BEGIN
IF Self IS TRttiInstanceProperty THEN
DEF:=TRttiInstanceProperty(Self).Default
ELSE
DEF:=0;
Result:=TValue.FromOrdinal(PropertyType.Handle,DEF)
END;
FUNCTION TPropertyHelper.IsOrdinal : BOOLEAN;
BEGIN
Result:=PropertyType.IsOrdinal
END;
PROCEDURE AssignDefaults(CONST [ref] O : TObject ; IncludeInherited : BOOLEAN = TRUE);
TYPE
TRttiProperties = TArray<TRttiProperty>;
VAR
CTX : TRttiContext;
ClassType : TRttiType;
Properties : TRttiProperties;
P : TRttiProperty;
BEGIN
CTX:=TRttiContext.Create;
ClassType:=CTX.GetType(O.ClassType);
IF IncludeInherited THEN Properties:=ClassType.GetProperties ELSE Properties:=ClassType.GetDeclaredProperties;
FOR P IN Properties DO IF P.IsWritable AND P.IsOrdinal AND (P IS TRttiInstanceProperty) THEN
P.SetValue(O,P.Default)
END;
</code>
<code>USES System.RTTI;
TYPE
TPropertyHelper = CLASS HELPER FOR TRttiProperty
FUNCTION IsOrdinal : BOOLEAN; INLINE;
FUNCTION Default : TValue;
END;
{ TPropertyHelper }
FUNCTION TPropertyHelper.Default : TValue;
VAR
DEF : INTEGER;
BEGIN
IF Self IS TRttiInstanceProperty THEN
DEF:=TRttiInstanceProperty(Self).Default
ELSE
DEF:=0;
Result:=TValue.FromOrdinal(PropertyType.Handle,DEF)
END;
FUNCTION TPropertyHelper.IsOrdinal : BOOLEAN;
BEGIN
Result:=PropertyType.IsOrdinal
END;
PROCEDURE AssignDefaults(CONST [ref] O : TObject ; IncludeInherited : BOOLEAN = TRUE);
TYPE
TRttiProperties = TArray<TRttiProperty>;
VAR
CTX : TRttiContext;
ClassType : TRttiType;
Properties : TRttiProperties;
P : TRttiProperty;
BEGIN
CTX:=TRttiContext.Create;
ClassType:=CTX.GetType(O.ClassType);
IF IncludeInherited THEN Properties:=ClassType.GetProperties ELSE Properties:=ClassType.GetDeclaredProperties;
FOR P IN Properties DO IF P.IsWritable AND P.IsOrdinal AND (P IS TRttiInstanceProperty) THEN
P.SetValue(O,P.Default)
END;
</code>
USES System.RTTI;
TYPE
TPropertyHelper = CLASS HELPER FOR TRttiProperty
FUNCTION IsOrdinal : BOOLEAN; INLINE;
FUNCTION Default : TValue;
END;
{ TPropertyHelper }
FUNCTION TPropertyHelper.Default : TValue;
VAR
DEF : INTEGER;
BEGIN
IF Self IS TRttiInstanceProperty THEN
DEF:=TRttiInstanceProperty(Self).Default
ELSE
DEF:=0;
Result:=TValue.FromOrdinal(PropertyType.Handle,DEF)
END;
FUNCTION TPropertyHelper.IsOrdinal : BOOLEAN;
BEGIN
Result:=PropertyType.IsOrdinal
END;
PROCEDURE AssignDefaults(CONST [ref] O : TObject ; IncludeInherited : BOOLEAN = TRUE);
TYPE
TRttiProperties = TArray<TRttiProperty>;
VAR
CTX : TRttiContext;
ClassType : TRttiType;
Properties : TRttiProperties;
P : TRttiProperty;
BEGIN
CTX:=TRttiContext.Create;
ClassType:=CTX.GetType(O.ClassType);
IF IncludeInherited THEN Properties:=ClassType.GetProperties ELSE Properties:=ClassType.GetDeclaredProperties;
FOR P IN Properties DO IF P.IsWritable AND P.IsOrdinal AND (P IS TRttiInstanceProperty) THEN
P.SetValue(O,P.Default)
END;