C# 如何将泛型类型参数传递给从构造函数调用的方法?

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时间:2020-08-10 14:24:46  来源:igfitidea点击:

How do I pass a generic type parameter to a method called from a constructor?

c#genericsconstructor

提问by Phil

Here is the constructor:

这是构造函数:

 public PartyRoleRelationship(PartyRole firstRole, PartyRole secondRole)
        {
            if (firstRole == secondRole)
                throw new Exception("PartyRoleRelationship cannot relate a single role to itself.");

            if (firstRole.OccupiedBy == null || secondRole.OccupiedBy == null)
                throw new Exception("One or both of the PartyRole parameters is not occupied by a party.");

            // Connect this relationship with the two roles.
            _FirstRole = firstRole;
            _SecondRole = secondRole;


            T = _FirstRole.GetType().MakeGenericType();

            _SecondRole.ProvisionRelationship<T>(_FirstRole); // Connect second role to this relationship.
        }

On the last line, where it calls ProvisionRelationship on _SecondRole, it's giving me the run-time error: Type or namespace 'T' could not be found...

在最后一行,它在 _SecondRole 上调用 ProvisionRelationship,它给了我运行时错误:找不到类型或命名空间“T”...

How do I either (a) properly assign T, or (b) pass a generic type with the constructor? I've been looking through quite a few posts, but may have missed something due to a lack of understanding. Anyone's help on this would be greatly appreciated.

我如何 (a) 正确分配 T,或 (b) 使用构造函数传递泛型类型?我已经浏览了很多帖子,但由于缺乏理解可能错过了一些东西。任何人对此的帮助将不胜感激。

采纳答案by Cheesebaron

Your class needs to be generic. So PartyRoleRelationshipneeds to look like this:

你的类需要是通用的。所以PartyRoleRelationship需要看起来像这样:

public class PartyRoleRelationship<T>
{
    public PartyRoleRelationship(T arg, ...)
    {
    }
}

Read more about generic classes here:

在此处阅读有关泛型类的更多信息:

http://msdn.microsoft.com/en-us/library/sz6zd40f(v=vs.80).aspx

http://msdn.microsoft.com/en-us/library/sz6zd40f(v=vs.80).aspx

http://msdn.microsoft.com/en-us/library/ms379564(v=vs.80).aspx

http://msdn.microsoft.com/en-us/library/ms379564(v=vs.80).aspx

Edit:

编辑:

You could probably simplify you code a bit and do it like this:

您可能可以稍微简化一下代码并这样做:

public class RoleRelationship<T>
{
    public RoleRelationship(T firstRole, T secondRole)
    {
        if (firstRole.OccupiedBy == null || secondRole.OccupiedBy == null)
            throw new Exception("One or both of the Role parameters is not occupied by a party.");

        // Connect this relationship with the two roles.
        _FirstRole = firstRole;
        _SecondRole = secondRole;

        _SecondRole.ProvisionRelationship<T>(_FirstRole);
    }
}

回答by user1610015

If you know the type of _FirstRole statically (is it PartyRole?), you can just use that:

如果您静态地知道 _FirstRole 的类型(它是 PartyRole 吗?),您可以使用它:

_SecondRole.ProvisionRelationship<PartyRole>(_FirstRole);

回答by Moop

Make a generic class where the generic type T is a type of the base class PartyRole:

创建一个泛型类,其中泛型类型 T 是基类 PartyRole 的一种类型:

public class PartyRoleRelationship<T> where T : PartyRole 
{
     T _FirstRole;
     T _SecondRole;

     public PartyRoleRelationship(T role1, T role2) {
         _FirstRole = role1;
         _SecondRole = role2;
         role1.ProvisionRelationship(role2)
     }

     public ProvisionRelationship(T otherRole) {
          // Do whatever you want here
     }

}