IMPRESSION SIMPLIFIÉE

...
public class FilePrinter: IPrintable
{
	public string _filename = null;

	public FilePrinter(){}

	public FilePrinter(string filename)
	{
		_filename = filename;
	}

	[DllImport("shell32.dll")]
	private static extern int ShellExecuteA(IntPtr hwnd,string operation,string file,string paramters,string directory,int showcmd);

	public void Print()
	{
		if (_filename != null)
			ShellExecuteA(IntPtr.Zero, "print", _filename, null, null, 0);
	}

	public string FileName
	{
		get
		{
			return _filename;
		}
		set
		{
			_filename = value;
		}
	}
}
...