改變

Question

我想知道是否有解決這一問題的根本途徑，其名稱被作爲輸入（帕斯卡）變量。也特別關注Pascal的特定解決方案。

讓我們說我們有2個輸入的一種形式：「傳遞InputVariable」和「inputValue將」。

在傳遞InputVariable區域的用戶類型，他想改變一個變量的名稱。在InputVALUE區域中，用戶鍵入此變量的值。

所以對於inputtexts '色' 和 '藍色'：我怎樣才能改變變量VAR_color不使用IF像語句：

If InputVARIABLE.Text = 'color' Then VAR_color := InputVALUE.Text; 

例如有沒有像一些功能：

ChangeVariable(InputVARIABLE.Text, InputValue.Text) 

希望你能幫助！

Answer 1

一般情況下，使用其名稱中的文本表示（串）

在Object Pascal /德爾福有一些這方面的擴展，但它們主要是指爲特定目的（您無法訪問的符號在帕斯卡通過如允許框架在不知道它的情況下對數據進行流式傳輸），而對於普通代碼則更少

因此，需要在規劃的變化。通常，你可以在一個變量名稱的數組中查找名字（或者如果是Object Pascal，則使用tstringlist），如果找到了有效的匹配，那麼你可以使用索引來設置數組中的結果。

Answer 2

如果您不需要更改delphi中預定義的實際變量，則可以實際執行其他操作。

所有你真正想要的是保存鍵 - 值對。

這在其他語言中被稱爲關聯數組/詞典/鍵值對

因此可以這樣說

Arr['color'] := 'red'; 

或者說

Arr[edit1.Text] := edit2.Text; 

反向

然後

Caption := Arr['color']; 

會將標題設置爲「紅色」或edit2.text中的任何內容，您可以根據需要添加任意數量的標題。

如果你有一個老版本的Delphi，你可以用Tlist類做同樣的事情，不要嵌套。

arr:= TStringList.Create; 
arr.Add('color=red'); 
s := arr.Values['color']; 
arr.free; 

我需要嵌套太多，所以我用做在Delphi XE3字典，可以幫助您更多的未來過於關聯數組類。

unit assoc; 

interface 

uses System.Generics.Collections, System.SysUtils; 

type TAssoc = class 
    private 
    fVal: Variant; 
    fStrict: Boolean; 
    fDict: TDictionary<Variant,TAssoc>; 
    function GetItem(Index: Variant): TAssoc; 
    procedure SetVal(v: Variant); 
    function GetVal:Variant; 
    public 
    /// <summary> 
    /// Returns the TAssocnode by default allowing you to chain Nodes  
    /// </summary> 
    /// <param name="Index"> 
    /// Search index, can be any primitive type. 
    /// </param> 
    property Items[Index: Variant]: TAssoc read GetItem; default; 

    /// <summary> 
    /// Use this to read and write a node value. 
    /// </summary> 
    /// <value> 
    /// can be almost everything Try not to use objects in here. 
    /// </value> 
    property Val:Variant read GetVal write SetVal; 

    /// <summary> 
    /// Gives you a direct link to the tdictionary object alowing you to 
    /// itterate 
    /// </summary> 
    property All:TDictionary<Variant,TAssoc> read fDict; 
    /// <summary> 
    /// <para> 
    ///  Usefull for creating keys in strict mode 
    /// </para> 
    /// <para> 
    ///  Array.add('key');<br />Array['key'].Val = 1; 
    /// </para> 
    /// <para> 
    ///  Wich would throw an error in strict mode as 'key' is not defined 
    ///  <br />In non strict mode it will just be created for you 
    /// </para> 
    /// </summary> 
    function Add(Index: Variant):TAssoc; overload; 
    /// <summary> 
    /// <para> 
    ///  Usefull for creating keys in strict mode and setting its value at the same time 
    /// </para> 
    /// <para> 
    ///  Array.add('key',1);<br />Array['key'].Val = 1; 
    /// </para> 
    /// <para> 
    ///  Wich would throw an error in strict mode as 'key' is not defined 
    ///  <br />In non strict mode it will just be created for you 
    /// </para> 
    /// </summary> 
    function Add(Index: Variant; Value: Variant):TAssoc; overload; 

    /// <summary> 
    /// Strictmode will raise an exception when you try to:<br />- set a nod 
    /// that was already set instead of overwriting it.<br />- read a node 
    /// that was nto set 
    /// </summary> 
    /// <param name="strictRules"> 
    /// Strictmode on of off 
    /// </param> 
    constructor Create(strictRules:Boolean); 
    destructor Free; 

    /// <summary> 
    /// Clears all underlying nodes 
    /// </summary> 
    procedure Clear; 
end; 

type TAssocEnum = TPair<Variant, TAssoc>; 

implementation 

{ TAssoc } 

function TAssoc.Add(Index: Variant): TAssoc; 
begin 
    Result := nil; 
    if(fDict<>nil) then begin // see if dict is or can be made 
    if(fDict.ContainsKey(Index)) then begin // see if the key is in there 
     if(fStrict = true) then begin // duplicate keys not strict 
     raise Exception.Create('Dictionary is in strict mode, the key "'+Index+'" was already set.'); 
     end; 
    end else begin // dict made, just not the key 
     Result := TAssoc.Create(fStrict); 
     fDict.Add(Index,Result); 
    end; 
    end else begin // dict not found 
    begin // make dict and key 
     fDict := TDictionary<Variant,TAssoc>.Create(1); 
     Result := TAssoc.Create(fStrict); 
     fDict.Add(Index,Result); 
    end; 
    end; 
end; 

function TAssoc.Add(Index, Value: Variant): TAssoc; 
begin 
    Result := Add(Index); 
    Result.Val := Value; 
end; 

procedure TAssoc.Clear; 
var 
    Enum: TPair<Variant, TAssoc>; 
begin 
    if(fDict<>nil) then begin 
    for Enum in fDict do begin 
     Enum.Value.Free; 
    end; 
    end; 
    fDict.Clear; 
end; 

constructor TAssoc.Create(strictRules:Boolean); 
begin 
    fStrict := strictRules; 
    fDict := nil; 
    TVarData(fVal).VType := varEmpty; 
end; 

destructor TAssoc.Free; 
var 
    Enum: TPair<Variant, TAssoc>; 
begin 
    if(fDict<>nil) then begin 
    for Enum in fDict do begin 
     Enum.Value.Free; 
    end; 
    end; 
end; 

function TAssoc.GetItem(Index: Variant): TAssoc; 
var 
    v: Variant; 
begin 
    Result := nil; 
    if(fdict<>nil) then begin // see if dict is or can be made 
    if(fDict.ContainsKey(Index)) then begin // see if the key is in there 
     Result := fDict.Items[Index]; 
    end else begin // dict made, just not the key 
     if (fStrict) then begin 
     raise Exception.Create('Dictionary is in strict mode, the key "'+Index+'" was not set.'); 
     end else begin // if not set, create the index and make it into a assocnode 
     Result := TAssoc.Create(fStrict); 
     fDict.Add(Index,Result); 
     end; 
    end; 
    end else begin // if the key is not in there see if strict or not 
    if(fStrict) then begin // if strict then error index not set 
     raise Exception.Create('Dictionary is in strict mode, the key "'+Index+'" was not set.'); 
    end else begin // if not set, create the index and make it into a assocnode 
     fDict := TDictionary<Variant,TAssoc>.Create(1); 
     Result := TAssoc.Create(fStrict); 
     fDict.Add(Index,Result); 
    end; 
    end; 
end; 

function TAssoc.GetVal: Variant; 
begin Result := fVal; end; 

procedure TAssoc.SetVal(v: Variant); 
begin fVal := v; end; 

// todo: 
// make a kickass helper class 
// output xml/json 
// walk through tree 
// parentnode property? 
// make a delphi7 version using stringlist? (not worth it) 
// have fun 

end. 

簡單的用法

Arr := TAssoc.Create(False); 
Arr['color'].Val := 'red'; 
Arr[edit1.text].Val := edit2.text; 
Arr.Free; 

高級用法

Arr := TAssoc.Create(False); 
Arr['cuzz']['cdcollection'][1]['name'].Val := 'Mika Album'; // set cd 
Arr['cuzz']['cdcollection'][2]['name'].Val := 1;   // set cd 
Arr['cuzz']['cdcollection'][1]['name'].Val := 'Delphi 5'; // overwrite cd 
Arr['cuzz']['cdcollection']['last']['name'].Val := 'Delphi xe3'; // overwrite cd 
// list all cd's 
for Enum in Arr['cuzz']['cdcollection'].All do begin 
    Memo1.Lines.Append('Property "'+String(Enum.Key)+'" holds "'+String(Enum.Value['name'].Val)); 
end; 
Arr.Free; 

德爾福石頭！ 享受。