[Boost-users] Odd limitation in Fusion design ?

Subject: [Boost-users] Odd limitation in Fusion design ?
From: John Dlugosz (JDlugosz_at_[hidden])
Date: 2010-07-07 20:40:18

I see that the "Cons" sequence is Forward-only.
reverse_view requires a Bidirectional sequence, at least.
The for_each iteration function goes forward.

However, hand-written recursive loop on a cons-like thing can do stuff before and other stuff after the recursive call to the cdr portion.  Putting stuff "after" will give a reversed processing.  So, in general, a reversed_for_each is not out of the question, and can be specialized for Cons when the general form of iterating backwards does not work.

I also ponder that a more general form that indeed does stuff before AND other stuff after recursing the tail would be a useful addition.  It might actually perform one operation iterating forward, then perform the other operation iterating backward back to the beginning; or use recursion; depending on the nature of the container.

--John






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