[.net] About Generic Methods

The part after the "where" clause states that the templated type this method accepts must inherit or derive from Resource class or interface, and that it must have an parameterless constructor (the new() part). The implementation of the method in your post requires that these two criterias are filled - the object is initialized with its default constructor and uses the non-templated Load method which it inherits from Resource base class or interface.

See "c# where clause" in MSDN for all possible uses.

EDIT: changed "empty" to "parameterless" to clarify - the constructor implementation can of course do what it needs to do.

The part after the "where" clause states that the templated type this method accepts must inherit or derive from Resource class or interface, and that it must have an parameterless constructor (the new() part). The implementation of the method in your post requires that these two criterias are filled - the object is initialized with its default constructor and uses the non-templated Load method which it inherits from Resource base class or interface.

See "c# where clause" in MSDN for all possible uses.

EDIT: changed "empty" to "parameterless" to clarify - the constructor implementation can of course do what it needs to do.

thx, that's what i've thought too ... why doesn't it work if i add the constructor to the Resource interface and remove the new from the where? that's what i've tried before

Without the constraint, there is no guarantee that the supplied type actually has a parameterless constructor (it is possible to mask out the default constructor of a base class in at least two ways). You have to take into account that the type could come from places other than the module in which the method is defined; not just your own code where you could implement the requirement loosely.

it is possible to mask out the default constructor of a base class in at least two ways

thx again
how could this be done ?

Way 1: define a constructor with parameters on the derived class, but omit the parameterless one. The derived class doesn't get the empty ctor from the base automatically, but the default constructor of the derived class would call the parameterless base ctor automatically if the derived class' ctor were actually generated. The definition of a parametrized constructor prevents the default ctor generation.

Way 2: create a dynamic class (with reflection) that derives from the base class. It doesn't inherit the base class ctor at all (though it has been a while since I tried this, this may have changed).

I don't remember whether or not it is the language's (c#) or CIL trait to generate the default ctor if no others exist. If other languages would not generate it, case two would apply there too.