Re: [ublas] Transition to default handling of possible lvalue aliases

From: Ian McCulloch (ianmcc_at_[hidden])
Date: 2005-06-24 14:18:04

David Abrahams wrote:

> Michael Stevens <mail_at_[hidden]> writes:
> 
>> Hi Jeff,
>>
>> On Monday 20 June 2005 16:07, Jeffrey McBeth wrote:
>>> Not that I should get a vote (having just joined the list and started
>>> using uBlas), but I'm all for the principle of least surprise.  We
>>> shouldn't have to flip a magic switch like alias() just to make the
>>> algorithm work right.  It should always work right.  The current
>>> no_alias paradigm is the right way to go.
>>
>> The problem now is that people are 'surprised' that either code is
>> suboptimal with regard to speed and temporaries.
>>
>> I think it is hard to avoid surprises!
> 
> If you're willing to have people be surprised that their object code is
> large you can avoid the other two surprises.

Can you explain more?  Except for some simple cases, determining whether
parameters are aliased cannot be done at compile-time, nor even an O(1)
runtime test.

Cheers,
Ian