C#

using UnityEngine;
using System.Collections;
 
public class ScrorpionControllerScript : MonoBehaviour 
{
	public float maxSpeed = 10f;
	bool facingRight = true;
 
	Animator anim;
 
	bool grounded = false;
	public Transform groundCheck;
	float groundRadius = 0.2f;
	public LayerMask whatIsGround;
	float jumpTime, jumpDelay = 0.2f;
	bool jumped;
	float punchTime, punchDelay = .5f;
	bool punch;
 

	// Use this for initialization
	void Start () 
	{
		anim = GetComponent<Animator> ();
	}
	
	// Update is called once per frame
	void FixedUpdate () 
	{
		grounded = Physics2D.OverlapCircle (groundCheck.position, groundRadius, whatIsGround);
		anim.SetBool ("Ground", grounded);
 
		anim.SetFloat ("vSpeed", rigidbody2D.velocity.y);
 
		anim.SetBool ("Ground", grounded);
 
		float move = Input.GetAxis ("Horizontal");
 
		anim.SetFloat ("wa", Mathf.Abs (move));
 
			rigidbody2D.velocity = new Vector2(move * maxSpeed, rigidbody2D.velocity.y);
 
		    if(move > 0 &&! facingRight)
			Flip ();
		    else if (move < 0 && facingRight)
			Flip ();
	}
 
	void Update()
	{
		if(Input.GetKeyDown (KeyCode.Space) && grounded)
		{
			rigidbody2D.AddForce(transform.up * 275f);
			jumpTime = jumpDelay;
			anim.SetTrigger("Jump");
			jumped = true;
		}
		jumpTime -= Time.deltaTime;
		if (jumpTime <= 0 && grounded && jumped) 
		{
	    	anim.SetTrigger ("Land");
			jumped = false;
		}
		if (Input.GetKeyDown (KeyCode.R));
		{
			punchTime = punchDelay;
			anim.SetTrigger("punch");
			punch = true;
		}
	}
 
	void Flip()
	{
		facingRight = !facingRight;
		Vector3 theScale = transform.localScale;
		theScale.x *= -1;
		transform.localScale = theScale;
	}
}

public class CMsg
{
    protected int m_Id;
}
public class CMsgTx : CMsg
{
    public string m_Dst;
}

public abstract class CNet
{
    abstract public int SendMsg(ref CMsg oMsg);
}
public class CNetSend : CNet
{
    override public int SendMsg(ref CMsg oMsg)
    {
        CMsgTx oTxMsg = oMsg as CMsgTx;
        return 1;
    }
}

{...
CMsgTx oMsg = new CMsgTx();
CNetSend oSender = new CNetSend()
 oSender.SendMsg(ref oMsg); // Error! 
...}