CODEWITHSUNDEEP
c#.netgenerics
Ricardo
Ricardo

Reputation: 468

How do I get the type of T inside a generic method?

I have the following generic method:

protected IEnumerable<T> GetAnimals<T>() where T : Animal
{
  // code
}

I may call this method using GetAnimals<Dog>() or GetAnimals<Cat>() where the Dog and Cat classes inherit from Animal.

What I need is to get the typeof(T) to find that the current method is executing with Dog or Cat. I've tried so far:

protected IEnumerable<T> GetAnimals<T>() where T : Animal
{
  bool isDog = typeof(T) is Dog ? true : false;
}

This typeof returns Animal and not Cat or Dog, so this is my issue.

One solution would be to create a method in Animal like WhatIAm() and implement it in Dog as return typeof(Dog) but I believe this is a bad solution.

Any advice?

Upvotes: 0

Views: 66

Answers (2)

Patrick Hofman
Patrick Hofman

Reputation: 156978

First, if you need a type check inside your generic method, maybe you are having the wrong approach / design. Generally this is considered bad design.

The actual solution to your problem:

bool isDog = typeof(T) == typeof(Dog);

Note that T must match Dog exact. Classes deriving from Dog are excluded.

A better approach might be:

bool isDog = typeof(Dog).IsAssignableFrom(typeof(T));

Also, you don't need the ternary operator.

Upvotes: 5

Selman Gen&#231;
Selman Gen&#231;

Reputation: 101681

You can compare the types directly

bool isDog = typeof(T) == typeof(Dog) ? true : false;

typeof(T) doesn't return Animal, it returns a type instance. is operator compares if the Type is compatible with Dog which is not because there is no relationship between Dog and type.

Upvotes: 2

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