[boost] Re: Are signals order same across platforms?

From: Nicolas Fleury (nfleury_at_[hidden])
Date: 2003-04-24 16:25:23

Douglas Gregor wrote:
> Yes, it would be very nice to have the ability to rely on the connection 
> order. I wouldn't want it to be a preprocessor option (too messy), although I 
> have considered a policy-based solution. The policy would dictate the 
> underlying storage mechanism, and therefore the ordering semantics. I'm just 
> leary of policy-based designs, because first we give a name to something 
> ("signal") but we then let its semantics vary wildly without changing its 
> syntax; in this case, the changes to the semantics are very subtle, and it 
> would be very easy to forget that signal A follows connection order whereas 
> signal B does not. 
> 
> I think if I were to go the policy-based route, I would want to introduce new 
> names. say, publisher/subscriber for the complete unordered versions, 
> delegates for connection-ordered versions, etc.

There's one advantage to the preprocessor option however.  Suppose you 
have an event-driven framework based on signals.  You might want the 
more optimized implementation, and therefore not condition-ordered, for 
most programs, but would like to make unit tests for this framework, and 
to ease their creation use the condition-ordered implementation.  It 
would however be an incomplete unit test since it would test only with a 
specific order.  If the performance is very similar for the 
connection-ordered solution, I guess this would not be an issue.  Do you 
have an idea what would be the cost in performance for 
connection-ordered signals?

By the way, congratulations for your work on boost::signals and to all 
people involved.

Regards,

Nicolas