thanks Theraot,
This is a great help! making the transition from C++ templates to C#
generics requries a change in mindset that I'm only now starting to
appreciate.
To answer your question in your response, by template I mean a generic
class rather than an Interface, i.e. the Interpolator<Method> class (C
++ progammers would call this a template, and an interface is
analogous to a virtual base class).
On Nov 3, 4:08 am, Theraot <[EMAIL PROTECTED]> wrote:
> I don't see any template, even more I haven't use them in C++. even
> that way, I can
> see interfaces and classes, and they have a lit problem:
>
> take out "public" from the method definition in the interface, to set
> public there is invalid.
> also, put "public" to the interface, because it is less accesible than
> the class implenting it, or else, take out public of the class (by
> default they are internal, that's package level).
>
> The interface now looks like this:
> public interface IBasisFunction1D
> {
> double Interpolate(double x, IList<double> xPoints,
> IList<double> yPoints);
> }
>
> Note that if you are writing a lib, and you has set the interface to
> public, that means that clients of your lib will be able to declare
> new types that implement that interface, if you don't want that,
> change it to internal, but you will need to change Interpolator to
> internal too.
>
> Ok, by member functions, I think you mean a method, and by template I
> think you mean Interface, if so... the main problem is that you are
> calling like this:
>
> Method.Interpolate(x, xPoints, yPoints);
>
> There "Method" is the name of the interface, and interfaces doesn't
> have static members, that means you
> need an object to be able to call "Interpolate" (that you know is not
> static anyway).
>
> We have generics, so first, change:
>
> public class Interpolator<Method>
> where Method : IBasisFunction1D
>
> to:
>
> public class Interpolator<Method>
> where Method : IBasisFunction1D, new()
>
> That's a generic constrain that tells C# that the type Method must
> have a public parameterless constructor that you will use (if you
> write none, the default one works just fine).
>
> That's just part of the problem, now we can create objects of type
> Method let's create one to call "Interpolate" and replace the invalid
> static call, so change:
>
> Method.Interpolate(x, xPoints, yPoints);
>
> to:
>
> (new Method()).Interpolate(x, xPoints, yPoints);
>
> Solved!!! but I has another suggestion:
>
> Cache that object, so no need to initialize a new one for every call.
> Including that, the final code (that I hope you understand, because if
> not, you will run in this problem again), is the following:
>
> public class Interpolator<Method> where Method : IBasisFunction1D,
> new()
> {
> private IBasisFunction1D cache; //this is a private field (a
> class level variable)
> public double Interp(double x, IList<double> xPoints,
> IList<double> yPoints)
> {
> //If cache is null (that's the default for classes) assign
> to it a new object of type Method (whatever it is)
> if (cache == null) cache = new Method();
> return cache.Interpolate(x, xPoints, yPoints); //Call with
> cache, that must has been initialized now
> //Note: if Method is a struct, it will never be null, but
> also you will not need to initialize it, so no problem.
> }//If you did copy -> paste, this is the proof of if, so easy
> this, but make sure of what this code does.
> }
>
> ... and so on ...
>
> you see? once understood, doing this in C# is trival.
> Don't get drown in a glass with water.
>
> ~Theraot
