Command.cs

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using System;
 
namespace DesignPatternExamples_csharp
{
    public class Command_TextObject
    {
        // Starting string text so we can reset the text to a known point.
        string _startingText;
 
        // The text that can change.
        string _text;
 
        public Command_TextObject(string text)
        {
            _text = text;
            _startingText = text;
        }
 
        public string Text
        {
            get
            {
                return _text;
            }
            set
            {
                _text = value;
            }
        }
 
        public void Reset()
        {
            _text = _startingText;
        }
 
 
        public override string ToString()
        {
            return _text;
        }
    }
 
 
    public delegate void two_parameter_operation(Command_TextObject source, string argument1, string argument2);
 
    public delegate void no_parameter_operation(Command_TextObject source);
 
 
    public class Command
    {
        // The receiver of the command.
        Command_TextObject _receiver;
 
        // Easy-to-read command name.
        string _commandName;
 
        // Two parameter operation to apply to the receiver.
        two_parameter_operation? _two_parameter_operation;
 
        // No parameter operation to apply to the receiver.
        no_parameter_operation? _no_parameter_operation;
 
        // The first argument to the operation.
        string _argument1;
 
        // The second argument to the operation.
        string _argument2;
 
        public Command(Command_TextObject source, string commandName, two_parameter_operation operation, string argument1, string argument2)
        {
            _receiver = source;
            _commandName = commandName;
            _two_parameter_operation = operation;
            _no_parameter_operation = null;
            _argument1 = argument1;
            _argument2 = argument2;
        }
 
        public Command(Command_TextObject source, string commandName, no_parameter_operation operation)
        {
            _receiver = source;
            _commandName = commandName;
            _no_parameter_operation = operation;
            _two_parameter_operation = null;
            _argument1 = string.Empty;
            _argument2 = string.Empty;
        }
 
        public void Execute()
        {
            if (_two_parameter_operation != null)
            {
                _two_parameter_operation(_receiver, _argument1, _argument2);
            }
            else if (_no_parameter_operation != null)
            {
                _no_parameter_operation(_receiver);
            }
        }
 
        public override string ToString()
        {
            string output = "<NO COMMAND>";
            if (_two_parameter_operation != null)
            {
                output = String.Format("{0} \"{1}\" with \"{2}\"", _commandName, _argument1, _argument2);
            }
            else if (_no_parameter_operation != null)
            {
                output = String.Format("{0}", _commandName);
            }
            return output;
        }
    }
}