RTTI动态数组TValue德尔福2010

问题描述

我有一个问题。我与运行时类型信息的新手，从2010年德尔福我需要设置长度动态数组成TValue。你可以看到code。

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;

我不喜欢泛型集合。

I don't like Generics Collections.

推荐答案

TValue 不是为（它会对如设置更多的帮手其内容任意操纵记录字段等等若有），而是对于混凝土静态类型和动态RTTI之间传输的值。在这方面， TValue.SetArrayElement 是一个异常，并在事后看来，或许不应该被包括在内。但是，你问什么是可能的：

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.

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