I have a question. I am a newbie with Run Time Type Information from Delphi 2010. I need to set length to a dynamic array into a TValue. You can see the code.
Type TMyArray = array of integer; TMyClass = class publihed function Do:TMyArray; end; function TMyClass.Do:TMyArray; begin SetLength(Result,5); for i:=0 to 4 Result[i]=3; end; ....... ....... ...... y:TValue; Param:array of TValue; ......... y=Methods[i].Invoke(Obj,Param);//delphi give me a DynArray type kind, is working, Param works to any functions. if Method[i].ReturnType.TypeKind = tkDynArray then//is working... begin I want to set length for y to 10000//i don't know how to write. end;
I don't like Generics Collections.
TValue wasn't designed for arbitrary manipulation of its contents (it would have more helpers for e.g. setting record fields etc. if so), but rather for transporting values between concrete static types and dynamic RTTI. In this respect, TValue.SetArrayElement is an anomaly, and in hindsight, perhaps should not have been included. However, what you ask is possible:
uses Rtti; type TMyArray = array of Integer; TMyClass = class function Go: TMyArray; end; function TMyClass.Go: TMyArray; var i: Integer; begin SetLength(Result, 5); for i := 0 to 4 do Result[i] := 3; end; procedure P; var ctx: TRttiContext; v: TValue; len: Longint; i: Integer; begin v := ctx.GetType(TMyClass).GetMethod('Go').Invoke(TMyClass.Create, []); Writeln(v.ToString); len := 10; DynArraySetLength(PPointer(v.GetReferenceToRawData)^, v.TypeInfo, 1, @len); Writeln(v.GetArrayLength); for i := 0 to v.GetArrayLength - 1 do Writeln(v.GetArrayElement(i).ToString); end; begin P; end.
