Delphi中匿名函数和泛型学习

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建议去万一博客学习泛型

此文参考：

https://blog.csdn.net/sndayYU/article/details/77401813

如何在Delphi中将泛型类型转换为实际类型 - 程序园  http://www.voidcn.com/article/p-fnhqdxab-bwh.html

https://blog.csdn.net/henreash/article/details/7048349

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------------------Unit

unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type

TMyClass = class
private
FSomeProp: String;
function GetSomeProp: String;
class function GetProp<T>(var ADataValue: T; const ARetriever: TFunc<T>): T;
public
property SomeProp:string read GetSomeProp;
end;

TForm1 = class(TForm)
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
uses
Generics.Collections, Generics.Defaults,TypInfo;
{$R *.dfm}
Type
TFun = function: string;
TReferenceFun = reference to function: string;
function TestFun: string;
begin
Result := '函数类型对象用法';
end;

procedure TForm1.Button1Click(Sender: TObject);
var
i:string;
begin
i:='1';
ShowMessage(TMyClass.GetProp<string>(i,TestFun));
end;

Procedure TForm1.FormCreate(Sender: TObject);
var
Fun: TFun;
RFun: TReferenceFun;
str: Integer;
begin
RFun :=function: string
begin
Result := '匿名函数reference用法';
end;
ShowMessage(RFun);
//Fun := TestFun;
//ShowMessage(Fun);

end;

class function TMyClass.GetProp<T>(var ADataValue: T; const ARetriever: TFunc<T>): T;
var
p:PTypeInfo;
aa:T;
{TTypeKind = (tkUnknown, tkInteger, tkChar, tkEnumeration, tkFloat,
tkString, tkSet, tkClass, tkMethod, tkWChar, tkLString, tkWString,
tkVariant, tkArray, tkRecord, tkInterface, tkInt64, tkDynArray, tkUString,
tkClassRef, tkPointer, tkProcedure)}
begin
p:=TypeInfo(T);
GetTypeData(p);
if p.Kind in [ tkString,tkUString] then
begin
Result:=ARetriever;
end;

end;

function TMyClass.GetSomeProp: String;
begin
Result := GetProp<String>(FSomeProp,
function: String
begin
Result := '';
end);
end;
end.

-----------------------------
procedure TForm1.CheckType<T>;
var
  p: PTypeInfo;
begin
  p := System.TypeInfo(T);
  case p.Kind of
    tkInteger, tkInt64:
    begin
      case GetTypeData(p).OrdType of
        otSByte: ShowMessage('SByte');
        otUByte: ShowMessage('UByte');
        otSWord: ShowMessage('SWord');
        otUWord: ShowMessage('UWord');
        otSLong: ShowMessage('SLong');
        otULong: ShowMessage('ULong');
      end;
    end;
    tkFloat:
    begin
      case GetTypeData(p).FloatType of
        ftSingle: ShowMessage('Single');
        ftDouble: ShowMessage('Double');
        ftExtended: ShowMessage('Extended');
        ftComp : ShowMessage('Comp');
        ftCurr: ShowMessage('Curr');
      end;
    end;
    tkChar: ShowMessage('Char');
    tkWChar: ShowMessage('WChar');

    tkEnumeration: ShowMessage('Boolean');//枚举类型或Boolean类型,需要加以区分
  end;
end;
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版权声明：本文为CSDN博主「henreash」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/henreash/article/details/7048349
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-------------------Unit

--------------Form

object Form1: TForm1
Left = 823
Top = 463
Caption = 'Form1'
ClientHeight = 277
ClientWidth = 389
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'MS Sans Serif'
Font.Style = []
OldCreateOrder = False
Position = poDesigned
OnCreate = FormCreate
PixelsPerInch = 96
TextHeight = 13
object Button1: TButton
Left = 160
Top = 152
Width = 75
Height = 25
Caption = 'Button1'
TabOrder = 0
OnClick = Button1Click
end
end

---------------Form