Re: Design for a file system library

From: dylan_nicholson (dylan_nicholson_at_[hidden])
Date: 2002-02-25 19:46:51

--- In boost_at_y..., Jan Langer <jan_at_l...> wrote:
> i uploaded a new version of filesystem which meets bemans 
requirements.
> 
> i have created a class attribute_set (according to dylans 
proposal). i
> implemented only three attributes to provide an example.

We need something better than require() for setting multiple 
properties:  Let's say I wanted to set the owner and group at the 
same time, and doing both together at the OS level would take half as 
long as doing one then the other.
The best I can think of is:

   attribute_set a(my_file_name);
   a.defer();
   a.set<owner>("dylan");
   a.set<group>("users");
   a.commit();

defer() and commit() again are completely optional.  If you only need 
one attribute, or don't care about the potential performance hit, 
then leave them out.  I would probably go further and say an 
implementation is allowed to ignore them too, so that failing to call 
commit() after defer() has an implementation-defined outcome.

(btw I really don't like the free function notation - it just looks 
atypical.  I understand it's purely a syntactical thing, but I think 
you'll find it matters more in many developers minds.  Also in this  
case for implementations that do honour require/defer/commit it 
probably requires a template friend declaration, which is not a good 
idea).

Dylan