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From: williamkempf_at_[hidden]
Date: 2001-03-22 11:31:49

--- In boost_at_y..., Jeremy Siek <jsiek_at_l...> wrote:
> On Thu, 22 Mar 2001 williamkempf_at_h... wrote:
> willia> I've been thinking about this, but haven't coded anything
up yet. Let
> willia> me ramble on about an implementation.
> willia>
> willia> namespace boost {
> willia> struct lock_tag { }
> willia> struct trylock_tag { }
> willia> struct timedlock_tag { }
> willia>
> willia> template <typename L>
> willia> struct lock_traits
> willia> {
> willia> typedef ... lock_category;
> willia> };
> willia> };
> One thing to keep in mind... the typical purpose of such categories
is for
> dispatching to different algorithms. However, off the top of my
head I
> can't imagine why someone would want to do this... isn't it the
case that
> if you need a trylock or timedlock, just a normal lock won't do?

One would assume this to be the case, yes, but I'm not 100% sure the
assumption will always be true. I'm feeling this suggestion out at
this point. I've not decided whether or not to go with this idea yet.

> willia> I can't see any other information that would go into a
> willia> type. Is there some useful type information that I'm not
thinking of
> willia> that should go in here?
> willia>
> willia> Also, one of the suggestions was to use a lock_category
type that
> willia> allows further decoupling of the lock types from the mutex
> willia> Usage was like this:
> willia>
> willia> boost::lock_category<boost::mutex>::trylock lock(mx);
> willia>
> willia> The problem with this is that there's not a one-to-one
> willia> of lock types to mutex types here. For instance, the
> willia> boost::fast_mutex doesn't have a trylock type. I can think
of a few
> willia> ways to deal with this but was interested in hearing
other's thoughts
> willia> on this and wondering if there's existing practice for this
sort of
> willia> thing.
> One way to handle this is to allow some types to be void. Another
> approach is to break the traits up.
> boost::trylock<boost::mutex>::type
> boost::lock<boost::mutex>::type

This looks awful similar to boost::basic_trylock and
boost::basic_lock. I realize the serve drastically different
purposes, but the names chosen here seem like they'd lead to
confusion about the purposes of the types.

Thanks for the thoughts.

Bill Kempf

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