[Dev-C++] newbie dynamic_cast question

[<tc...@gm...>]

Hi all,

I have a dynamic_cast problem and I am not comming forward since then in 
my project. Therefore I decided too find some help here in ths ML.

OK,

I actually want to implement the iterator design Pattern in order to 
iterate through abstract Elements of abstract CollectionObjects. 
Therefore I have a class Element and CollectionObject.

Now I have written some concrete implementing classes Directory and File 
that are supposed to be both Elements, with the supplement that 
Directory is also a CollectionObject.

So I have sth. like

class Element{...}

class FileSystem : public Element { }

class File : public FileSystem {...}

class Directory : public CollectionObject, public FileSystem { ... }

Now I decided to include some Filters, Iteated elements should be 
matched by Patterns (abstract class). I have created for this one a 
PatternExtension concrete class. It all looks lie this:

class Pattern {
...
public:
	virtual bool match( Element *p_Element ) = 0;
}


class PatternExtension : public Pattern
{
	...
	virtual bool match( Element *p_Element )
	{
		//here starts the problem:
		//writing this instruction is causes an Error from the 				//compiler. 
Therefore I have been looking in my doc.
		//and I am convince to be doing it properly....

	    File *l_File;

	    if( l_File = dynamic_cast<File *>( p_Element ) != NULL )
		{
		...
		}
	/*
		Compiler error message:

PatternExtension.cpp:19: cannot dynamic_cast `p_Element' (of type `class 
fs::Element *') to type `class fs::File *'
make[1]: *** [PatternExtension.o] Fehler 1
make[1]: Verlassen des Verzeichnisses Verzeichnis 
»/work/Projects/C++/Project1/fs«
make: *** [all] Fehler 2
	*/
	}
}

Why then?

I hope I wasn't too long and that I made myself clear enough. I would be 
pleased for any hint, tip to help me comming forward.

Thanx

--
Eric Tchepannou