Reflection question

[Acidburn]

Hey there,

I'm quite new to C# but have an extensive background in Java so I know all the basics and perhaps more. But I've found i'm struggling with C#'s answer to dynamic binding at runtime.

Whilst Java can take a namespace entry from an interface and turn it into a class instance it appears that C# can't? Perhaps I'm doing it wrong but I've looked into the System.Reflection namespace and nothing appears to work like Java does.

now in Java the Class is actually a Class of type Class. Meaning you can instaniate a class of this type which is derived from Object. C# doesn't have this but yet you can still query meta data on the class required.

Is there a way to get C# to construct an object of a class from an interface namespace?

Hope this makes sense, if not I can post more information.

[LizR]

Yes. You can walk through the classes/structs etc of an application and then create instances.

For example

Assembly a = null;
            AssemblyName n = new AssemblyName("mynamespace");
            a = Assembly.Load(n);
            Type[] ts = a.GetTypes();

            foreach (Type t in ts)
            {
                
                if (t.Name == "MyClass")
                {
                    newcmd = (MyClass)Activator.CreateInstance(t);

                }
            }

Will go through your code and make an instance of "MyClass" theres probably a quicker way but I took that from some of my code I use to walk through and make instances of all things derrived from a specific class.

[Acidburn]

One question from that, whats newcmd?

[LizR]

Its an instance of my class so its defined as the base class.

[Acidburn]

hmm,so you can't pass a class into a method and cast it?

Eg

loadAllClasses(class T) {

//load through all DLL's...

create object of type T

return T

Basically all i need to do is create classes on the fly and add them to a HashMap<class>, or something of a smiliar nature, then use an singleton, factory class to obtain a layer of seperation in my applciation. this will allow for a text file to decide which classes are loaded at runtime.

I'm beginning to think this isn't possible in C#?

[LizR]

Probably but you could probably do it based around the code I gave but I havent needed to go deeper than that

[fuzzelogic]

Hi! If you looking for something like java's Create proxy, C# does not have it built in. here's a link to a solution ... http://www.codeproject.com/KB/cs/dynamicproxy.aspx

[Acidburn]

Hi! If you looking for something like java's Create proxy, C# does not have it built in. here's a link to a solution ... http://www.codeproject.com/KB/cs/dynamicproxy.aspx

I'm not sure its proxy that I'm looking for? Perhaps the name deems that opinion. Here's more information on what I'm trying to acheive.

-----------

I've got an interface called DAOInterface, which can have 2 implementations. 1 which updates the database, the other which just soley updates member variables - doesn't use the database, this is ideal for demonstrations.

So i was wondering if I could produce a class out of the interface namespace. Say for example if I had a text file that said:

#Interface=classpath

com.john.DAOInterface=com.john.DAOInstance

this would provide the path of the interface and the direct path to the class that I need.

Can C# do this? The 'class' is just a keyword, where is Java its an actual object.

doing the following in Java is perfectly legal HashMap<Class, Class> where is C# its not!

[LizR]

But as long as they descend from the same base ansestor you could do it, and using code similar to that, and like what I gave you

[Acidburn]

The obly bit I'm struggling with is creating an HashMap that takes classes, otherwise how am I going to say

GetClass(x) where X is a key if they are all objects? Somewhere I'd have to cast it to the child object but knowing which object I've got would be ideal

[fuzzelogic]

Hi .. Is what u looking for generics.. ie..
Dictionary<TInterfaceType,object> hash = new Dictionary<TInterfaceType,object>();

then in code you use the interface type as the type???

Is that what u looking for !!

[Acidburn]

How can you the interface type has the type? Its just an interface in C# rather than a class isn't it?

[fuzzelogic]

Doh ! use the ineterface as the KEY no the type .. sorry!