我想知道是否有解决此问题的基本方法。对Pascal的特定解决方案也特别感兴趣。
假设我们有一个包含2个输入的表单：'InputVARIABLE'和'InputVALUE'。
在InputVARIABLE区域中，用户键入要更改的变量的名称。在InputVALUE区域中，用户键入此变量的值。
因此对于inputtexts'color'和'blue'：如何在不使用IF语句的情况下更改变量VAR_color：
If InputVARIABLE.Text = 'color' Then VAR_color := InputVALUE.Text;
是否有一些功能，如：
ChangeVariable(InputVARIABLE.Text, InputValue.Text)
希望你能帮忙！
答案 0 :(得分：8)
如果您不需要更改在delphi中预定义的实际变量，您实际上可以执行其他操作。
你真正想要的是保存键值对。
这在其他语言中称为关联数组/字典/键值对
所以你可以说
Arr['color'] := 'red';
或者说
Arr[edit1.Text] := edit2.Text;
然后反向
Caption := Arr['color'];
会将标题设置为'red'或edit2.text中的任何内容，您可以根据需要添加任意数量。
如果你有一个旧版本的Delphi，你可以对Tlist类做同样的事情，而不是嵌套。
arr:= TStringList.Create;
arr.Add('color=red');
s := arr.Values['color'];
arr.free;
我也需要嵌套，所以我使用delphi XE3中的字典创建了一个关联数组类，这可能会在将来帮助你。
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.
简单用法
Arr := TAssoc.Create(False);
Arr['color'].Val := 'red';
Arr[edit1.text].Val := edit2.text;
Arr.Free;
高级用法
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;
答案 1 :(得分：2)
通常，您无法在文本表示（字符串）
中使用其名称访问Pascal中的符号Object Pascal / Delphi对此有一些扩展，但它们主要用于特定目的（例如允许框架在不知道的情况下流式传输数据），而对于普通代码则更少。
因此需要改变计划。通常在变量名数组中查找名称（如果找到Object Pascal，则查找tstringlist），如果找到有效匹配，则使用索引在数组中设置结果。