Re: [Boost-users] BOOST_FOREACH and iterating by reference

From: Daniel Gehriger (gehriger_at_[hidden])
Date: 2007-05-24 16:23:48

Eric Niebler wrote:
> 
> Are you saying that calling o.destroy() causes "it" to  be invalidated? 
> This is bad practice. If that's not the case, then vanilla FOREACH 
> should meet your needs. Please correct me if I've misunderstood your 
> situation.
> 

Yes, exactly. I wouldn't do that usually, but the collection is in fact a
database table, and I use the iterators to access the records. Each record
contains a field with the index of the next record (basically a
singly-linked list). Destroying the record therefore invalidates the
iterator pointing to the record. Pre-incrementing, however, works fine.

A solution would be to cache all indices when accessing the collection, but
I can't afford the overhead for this.

Maybe this case is too specialized for Boost and doesn't warrant the
inclusion of a BOOST_FOREACH_PRE macro in the library.

- Daniel

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