scope(exit)

[MM]

>Personally, I find the basic guarantee to be of very limited use.  For 
>most operations, the weak guarantee seems far more appropriate, and I 
>believe it is reasonable to expect that of the lock function.  In other 
>words, if the lock function fails then I would expect m to be in the 
>state it was in prior to the lock call.  Further, it's possible that 
>unlock might consider being asked to unlock a mutex that the calling 
>thread doesn't own to be an error condition, which may result in an 
>exception being generated.  Therefore, if lock fails and throws and 
>exception and scope(exit) unlock(m) therefore fails and throws an 
>exception as well, the application will terminate because it has two 
>exceptions in flight simultaneously.  Therefore:
>
>     lock(m);
>     scope(exit) unlock(m);
>
>is preferred because unlock will only be called if a lock was 
>successfully obtained, and will be called regardless of whether the 
>following code generates an error or completes successfully.
>
>
>Sean

Lock && unlock could ofcourse be any arbitrary function.. thus I was asking
myself, why use the weak guarantee? When you take the change on a fault in lock
at about the same as unlock your reasoning would be sound. But most of the
time(in my code:) the 'unlock' function is far less complex than the 'lock'
function.
Is it then still better to use the weak guarantee?(not a retoric question... :)