[英]How to check if a generic has an operator? C#
我想為泛型類重載operator +(f,s)。 如果f和s具有加號運算符,則應返回+(f,s),否則返回null。 我該怎么做?
public class param<T> : TDefault
{
public string param_name;
public T cnt;
public param(T _cnt)
{
cnt=_cnt;
}
public static param<T> operator +(param<T> f, param<T> s)
{
if(T ? has_operator("+"))
return param<T>(((f.cnt as ?)+(s.cnt as ?)) as T);
return null;
}
}
為了檢查操作員的存在,我試過
public static bool has_method(this object target,string method_name)
{
return target.GetType().GetMethod(method_name)!=null;
}
但
int x;
print (x.has_method("+="));
打印'假'
嘗試這個:
public class Param<T>
{
private static readonly Func<T, T, T> addMethod;
static Param()
{
try
{
ParameterExpression left = Expression.Parameter(typeof (T), "left");
ParameterExpression right = Expression.Parameter(typeof (T), "right");
addMethod = Expression.Lambda<Func<T, T, T>>(Expression.Add(left, right), left, right).Compile();
}
catch (InvalidOperationException)
{
//Eat the exception, no + operator defined :(
}
}
public string param_name;
public T cnt;
public Param(T _cnt)
{
cnt = _cnt;
}
public static Param<T> operator +(Param<T> leftOperand, Param<T> rightOperand)
{
if (addMethod != null)
{
return new Param<T>(addMethod(leftOperand.cnt, rightOperand.cnt));
}
return null;
}
}
private static void Main(string[] args)
{
var pi = new Param<int>(5);
var pi2 = new Param<int>(6);
var pi3 = pi + pi2;
var pi4 = new Param<ooject>(5);//Wont work
var pi5 = new Param<object>(6);
var pi6 = pi4 + pi5;
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.