Delphi 2010 中的泛型

Author：傻猫
发布时间：June 27, 2010
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Categories：搞软件

2010已发布很长时间了，口碑还不错，准备用它开发下一项目，但对泛型等新东西的认识还不够，就搜了一下，发现下面这篇文章，还不错，大家一起补补课吧！
C++中的模板、C#等语言中泛型技术，给许多操作不同类型数据的软件人员提供了一个很好的方法。其类型的&ldquo;可变&rdquo;性，让许多用过的软件人员所心喜。但是在Delphi 2009以前的版本中，是从来没有的。让许多不会用Delphi中TList的人员，大大的抱怨。如果用好Delphi中TList，其可用性，我个人认为，比其它语言中的泛型好用很多（当然对指针的应用和内存的分配、释放不了解的人除外）。
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 自从Delphi 2009的发布，给许多喜欢用泛型技术的软件人员，提供了方便。由于Delphi 2009不太稳定，也没有过多的去用其泛型技术。Delphi 2010发布以来，出现许多&ldquo;Delphi 2010初体验，是时候抛弃Delphi 7了&rdquo;的话语的满天飞，让我想一看其究竟。

&nbsp;&nbsp;&nbsp;&nbsp; 闲话少说，Delphi 2010的泛型单元Generics.Defaults、Generics.Collections；重点还是Generics.Collections单元，其中有TArray泛型类、TList&lt;T&gt;（列表的泛型）、TQueue&lt;T&gt;（队列的泛型）、TStack&lt;T&gt; （栈的泛型）、TDictionary&lt;TKey,TValue&gt; （Hash Table哈希表的泛型）及其上述泛型所对应的TObject的泛型，非常广泛。
简单的泛型类应用：(转)
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unit Unit1;
interface
uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls;
type TForm1 = class(TForm) &nbsp;&nbsp;&nbsp; Memo1: TMemo; &nbsp;&nbsp;&nbsp; Edit1: TEdit; &nbsp;&nbsp;&nbsp; Edit2: TEdit; &nbsp;&nbsp;&nbsp; Button1: TButton; &nbsp;&nbsp;&nbsp; Button2: TButton; &nbsp;&nbsp;&nbsp; Button3: TButton; &nbsp;&nbsp;&nbsp; Button4: TButton; &nbsp;&nbsp;&nbsp; procedure FormCreate(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure FormDestroy(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button1Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button2Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button3Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button4Click(Sender: TObject); end;
var Form1: TForm1;
implementation
{$R *.dfm}
uses Generics.Collections; {Delphi 泛型容器单元}
var Dictionary: TDictionary&lt;Cardinal,string&gt;; {定义一个泛型 TDictionary 类, 指定有 Cardinal、string 构成}
{建立} procedure TForm1.FormCreate(Sender: TObject); begin Dictionary := TDictionary&lt;Cardinal,string&gt;.Create;
Memo1.Clear; Button1.Caption := Button1.Caption + ' 添加'; Button2.Caption := Button2.Caption + ' 删除'; Button3.Caption := Button3.Caption + ' 尝试取值'; Button4.Caption := Button4.Caption + ' 清空';
Edit1.Clear; Edit2.Clear; Edit1.NumbersOnly := True; end;
{释放} procedure TForm1.FormDestroy(Sender: TObject); begin Dictionary.Free; end;
{添加} procedure TForm1.Button1Click(Sender: TObject); var key: Cardinal; value: string; str: string; k,v: Boolean; begin key := StrToIntDef(Edit1.Text, 0); value := Edit2.Text; if value = '' then value := 'Null';
k := Dictionary.ContainsKey(key);&nbsp;&nbsp;&nbsp;&nbsp; {Key 是否存在} v := Dictionary.ContainsValue(value); {Value 是否存在}
if not k then begin &nbsp;&nbsp;&nbsp; Dictionary.Add(key, value); &nbsp;&nbsp;&nbsp; Memo1.Lines.Add(Format('%d=%s', [key, value])); {同步显示} end;
if k and not v then begin &nbsp;&nbsp;&nbsp; str := Format('key 已存在: %d=%s; 是否修改其值?', [key, Dictionary[key]]); &nbsp;&nbsp;&nbsp; if MessageBox(0, PChar(str), '提示', MB_OKCANCEL or MB_ICONQUESTION) = mrOk then &nbsp;&nbsp;&nbsp; begin &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //Dictionary[key] := value; {Dictionary[key] = Dictionary.Item[key]} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Dictionary.AddOrSetValue(key, value);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {也可使用上一句} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Memo1.Lines.Values[IntToStr(key)] := value; {同步显示} &nbsp;&nbsp;&nbsp; end; end;
if k and v then begin &nbsp;&nbsp;&nbsp; str := Format('%d=%s 已存在, 不能重复添加', [key, value]); &nbsp;&nbsp;&nbsp; MessageBox(0, PChar(str), '错误', MB_OK + MB_ICONHAND); end;
Text := IntToStr(Dictionary.Count); end;
{删除: Remove} procedure TForm1.Button2Click(Sender: TObject); var key: Integer; i: Integer; begin key := StrToIntDef(Edit1.Text, 0);
if not Dictionary.ContainsKey(key) then begin &nbsp;&nbsp;&nbsp; ShowMessageFmt('key: %d 不存在', [key]); &nbsp;&nbsp;&nbsp; Exit; end; &nbsp;&nbsp;&nbsp; Dictionary.Remove(key); Text := IntToStr(Dictionary.Count);
{同步显示} i := Memo1.Lines.IndexOfName(IntToStr(key)); if i &gt; -1 then Memo1.Lines.Delete(i); end;
{尝试取值: TryGetValue} procedure TForm1.Button3Click(Sender: TObject); var key: Integer; value: string; begin key := StrToIntDef(Edit1.Text, 0); if Dictionary.TryGetValue(key, value) then &nbsp;&nbsp;&nbsp; ShowMessageFmt('key: %d 已存在, 其值是: %s', [key, value]) else &nbsp;&nbsp;&nbsp; ShowMessageFmt('key: %d 不存在', [key]) end;
{清空: Clear} procedure TForm1.Button4Click(Sender: TObject); begin Dictionary.Clear; Text := IntToStr(Dictionary.Count); Memo1.Clear; {同步显示} end;
end.
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自定义泛型应用:(转)
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unit Unit1;
interface
uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls;
type TForm1 = class(TForm) &nbsp;&nbsp;&nbsp; Memo1: TMemo; &nbsp;&nbsp;&nbsp; Button1: TButton; &nbsp;&nbsp;&nbsp; Button2: TButton; &nbsp;&nbsp;&nbsp; Button3: TButton; &nbsp;&nbsp;&nbsp; Button4: TButton; &nbsp;&nbsp;&nbsp; Button5: TButton; &nbsp;&nbsp;&nbsp; procedure Button1Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button2Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button3Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button4Click(Sender: TObject); &nbsp;&nbsp;&nbsp; procedure Button5Click(Sender: TObject); end;
var Form1: TForm1;
implementation
{$R *.dfm}
type TArr&lt;T&gt; = array[0..9] of T; {定义一个泛型数组} {虽然大家习惯用 T 来泛指其他类型, 但使用其他合法的标识符也是可以的}
{用作 Integer} procedure TForm1.Button1Click(Sender: TObject); var Arr: TArr&lt;Integer&gt;; i: Integer; begin for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Arr[i] := i * i;
Memo1.Clear; for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Memo1.Lines.Add(Format('Arr[%d] = %d', [i, Arr[i]])); end;
{用作 string} procedure TForm1.Button2Click(Sender: TObject); var Arr: TArr&lt;string&gt;; i: Integer; begin for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Arr[i] := StringOfChar(Char(i+97), 3);
Memo1.Clear; for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Memo1.Lines.Add(Format('Arr[%d] = %s', [i, Arr[i]])); end;
{用作 Single} procedure TForm1.Button3Click(Sender: TObject); var Arr: TArr&lt;Single&gt;; i: Integer; begin for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Arr[i] := 100 / (i+1);
Memo1.Clear; for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Memo1.Lines.Add(Format('Arr[%d] = %f', [i, Arr[i]])); end;
{用作记录 TPoint} procedure TForm1.Button4Click(Sender: TObject); var Arr: TArr&lt;TPoint&gt;; i: Integer; begin for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Arr[i] := Point(i, i*2);
Memo1.Clear; for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Memo1.Lines.Add(Format('Arr[%d] = (%d,%d)', [i, Arr[i].X, Arr[i].Y])); end;
{用作类 TButton} procedure TForm1.Button5Click(Sender: TObject); var Arr: TArr&lt;TButton&gt;; i: Integer; begin for i := Low(Arr) to High(Arr) do begin &nbsp;&nbsp;&nbsp; Arr[i] := TButton.Create(Self); &nbsp;&nbsp;&nbsp; Arr[i].Name := Concat('Btn', IntToStr(i+1)); end;
Memo1.Clear; for i := Low(Arr) to High(Arr) do &nbsp;&nbsp;&nbsp; Memo1.Lines.Add(Format('Arr[%d] is %s', [i, Arr[i].Name])); end;
end.
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