TUpperCaseString auto-converts assigned string to uppercase (with property editor and example component)

Test.UpperCaseString.Design.pas

unit Test.UpperCaseString.Design;

interface

procedure Register;

implementation

uses
  System.Classes,
  Test.UpperCaseString;

procedure Register;
begin
  RegisterComponents('Samples', [TTestUpperCaseString]);
end;

end.

Test.UpperCaseString.pas

unit Test.UpperCaseString;

interface

uses
  System.Classes,
  UpperCaseString.Types;

type
  TTestUpperCaseString = class(TComponent)
  private
    FCaptionUpper: TUpperCaseString;
  published
    property CaptionUpper: TUpperCaseString read FCaptionUpper write FCaptionUpper;
  end;

implementation

end.

UpperCaseString.Design.pas

unit UpperCaseString.Design;

interface

uses
  DesignEditors;

type
  TUpperCaseStringEditor = class(TPropertyEditor)
  public
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

procedure Register;

implementation

uses
  System.Rtti,
  DesignIntf,
  UpperCaseString.Types;

procedure Register;
begin
  RegisterPropertyEditor(TypeInfo(TUpperCaseString), nil, '', TUpperCaseStringEditor);
end;

function TUpperCaseStringEditor.GetValue: string;
begin
  var context := TRttiContext.Create;
  var instance := GetComponent(0);
  var typ := context.GetType(instance.ClassType);
  var prop := typ.GetProperty(GetPropInfo.Name);
  var value := prop.GetValue(instance);
  Result := value.AsType<TUpperCaseString>;
end;

procedure TUpperCaseStringEditor.SetValue(const Value: string);
begin
  var context := TRttiContext.Create;
  var instance := GetComponent(0);
  var typ := context.GetType(instance.ClassType);
  var prop := typ.GetProperty(GetPropInfo.Name);
  prop.SetValue(instance, TValue.From<TUpperCaseString>(Value));
end;

end.

UpperCaseString.Types.pas

unit UpperCaseString.Types;

interface

type
  TUpperCaseString = record
  private
    FValue: string;
  public
    class operator Implicit(A: TUpperCaseString): string; overload;
    class operator Implicit(A: string): TUpperCaseString; overload;
  end;

implementation

uses
  System.SysUtils;

class operator TUpperCaseString.Implicit(A: TUpperCaseString): string;
begin
  Result := A.FValue;
end;

class operator TUpperCaseString.Implicit(A: string): TUpperCaseString;
begin
  Result.FValue := A.ToUpper;
end;

end.