将方法组转换为表达式 [英] Convert Method Group to Expression

问题描述

我试图弄清楚如果有一个简单的语法将方法组转换为表达式。对于lambdas来说看起来很简单，但不能转化为方法：

给定

 public delegate int FuncIntInt（int x）; 
  

以下所有内容均有效：

  Func< int，int> func1 = x => X; 
 FuncIntInt del1 = x => X; 
表达式< Func< int，int>> funcExpr1 = x => X; 
表达式< FuncIntInt> delExpr1 = x => X; 
  

但是，如果我尝试与实例方法相同，则会在表达式中分解：

  Foo foo = new Foo（）; 
 Func< int，int> func2 = foo.AFuncIntInt; 
 FuncIntInt del2 = foo.AFuncIntInt; 
表达式< Func< int，int>> funcExpr2 = foo.AFuncIntInt; //不编译
表达式&FunCIntInt> delExpr2 = foo.AFuncIntInt; //不编译
  

最后两个都无法使用无法转换方法组AFuncIntInt '到非委托类型'System.Linq.Expressions.Expression< ...>'你打算调用该方法吗？

那么有一个很好的谢谢，b
$ b

解决方案

这个怎么样？

 表达式< Func< int，int>> funcExpr2 =（pArg）=> foo.AFuncIntInt（PARG）; 
表达式< FuncIntInt> delExpr2 =（pArg）=> foo.AFuncIntInt（PARG）; 
  

I'm trying to figure out of if there is a simple syntax for converting a Method Group to an expression. It seems easy enough with lambdas, but it doesn't translate to methods:

Given

public delegate int FuncIntInt(int x);

all of the below are valid:

Func<int, int> func1 = x => x;
FuncIntInt del1 = x => x;
Expression<Func<int, int>> funcExpr1 = x => x;
Expression<FuncIntInt> delExpr1 = x => x;

But if i try the same with an instance method, it breaks down at the Expressions:

Foo foo = new Foo();
Func<int, int> func2 = foo.AFuncIntInt;
FuncIntInt del2 = foo.AFuncIntInt;
Expression<Func<int, int>> funcExpr2 = foo.AFuncIntInt; // does not compile
Expression<FuncIntInt> delExpr2 = foo.AFuncIntInt;      //does not compile

Both of the last two fail to compile with "Cannot convert method group 'AFuncIntInt' to non-delegate type 'System.Linq.Expressions.Expression<...>'. Did you intend to invoke the method?"

So is there a good syntax for capturing a method grou in an expression?

thanks, arne

解决方案

How about this?

  Expression<Func<int, int>> funcExpr2 = (pArg) => foo.AFuncIntInt(pArg);
  Expression<FuncIntInt> delExpr2 = (pArg) => foo.AFuncIntInt(pArg);

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