[SAGA-RG] Semantics of the ns_entry constructor

[Andre Merzky]

Quoting [Ceriel Jacobs] (Aug 17 2009):
> 
> Andre Merzky wrote:
>
>> You are right: open should be able to open entries and
>> directories (which *are* entries).  open_dir should work
>> only for directories.  Same holds then indeed for the entry
>> and dir constructors.
> 
> Are you sure? I have an issue with what you are saying about the
> entry constructor. I think that if a ns_entry object represents
> a directory, it should in fact be a ns_directory object.

Well, directory inherits entry, so you can alw2ays do:

  saga::url         u ("file://localhost/etc/")
  saga::file::dir   d (u);
  saga::file::entry e = d; // downcast should always work

  std::cout << u << " is dir:   " << e.is_dir () << std::endl;
  std::cout << u << " is entry: " << e.is_dir () << std::endl;


is_dir would return true, is_entry would return false.
Sure, sounds strange that is_entry() can return false on an
entry, but it is defined as:

 - the method returns false if the entry is a link or a
   directory (although an ns_directory IS_A ns_entry, false
   is returned on a test on an ns_directory) - otherwise
   true is returned. 


If the above works, I don't see why 

  saga::file::entry e (u);

should not work.  Or am I missing something?  The same then
also holds for the open methods - the origin of Matijs'
complain.

Best, Andre.



> Cheers,		Ceriel



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