Type of restriction for certain types

Question

Is it possible to restrict the general method to certain types?

I want to write something like this:

public T GetValue<T>(string _attributeValue) where T : float, string
{
    return default(T); // do some other stuff in reality
}

I am just trying to avoid creating a gigantic expression switchinside a method or having to throw an exception if an invalid type is specified.

Edit: Ack. I knew it was stringnot a type of value. I started with two number types before. Unfortunately.

Answer 1

, , . - , ( , ).

. , , .

, . , - . , .

float GetFloat(string attrName) { }
string GetString(string attrName) { }

" ", . , , . , , ( ). , - , (int vs. uint long).

float GetValue(string attrName, float defaultValue) { ... }
string GetValue(string attrName, string defaultValue) { ... }

, , , . , - , . ( , , ). , - , ... ( ) .

T GetValue<T>( string attrName )
{
   if( typeof(T) != typeof(string) ||
       typeof(T) != typeof(float) )
       throw new NotSupportedException();
   return default(T); 
}

// call it by specifying the type expected...
float f = GetValue<float>(attrName);
string s = GetValue<string>(attrName);

out . , , , .

void GetValue( string attrName, out float value )
void GetValue( string attrName, out string value )

// example of usage:
float f;
GetValue( attrName, out f );
string s;
GetValue( attrName, out s );

Answer 2

. ( , T ) ( ) , .

Answer 3

, .

, .

, , ( Nullable types):

public T GetValue<T>(string _attributeValue) where T : struct

, , ( /). , ...

Another option may also be to make your method confidential and provide special wrappers that are specific:

private T GetValue<T>(string _attributeValue) where T : struct
{
    return default(T);
}

public float GetFloatValue(string _attributeValue)
{
    return GetValue<float>(_attributeValue);
}

public int GetIntValue(string _attributeValue)
{
    return GetValue<int>(_attributeValue);
}

This will allow you to limit the public members of your class to the desired types, but still use the common code inside, so you don't need to repeat yourself.

Answer 4

No, you cannot specify a range of types. If you want all the primitives you can do (and I know the line is not included)

 where T: struct