我有个问题.我是Delphi 2010中运行时类型信息的新手.我需要将动态数组的长度设置为TValue.你可以看到代码.
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Generics Collections.
解决方法
TValue不是为了对其内容进行任意操作而设计的(如果是这样的话,它将有更多帮助器用于设置记录字段等),而是用于在具体静态类型和动态RTTI之间传输值.在这方面,TValue.SetArrayElement是一个异常,事后看来,或许不应该被包括在内.但是,你问的是可能的：
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.