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From: Dave Harris (brangdon_at_[hidden])
Date: 2005-05-02 05:23:32

In-Reply-To: <20050430145039.A20350_at_[hidden]>
ikh_at_[hidden] (Iain K. Hanson) wrote (abridged):
> I really don't like macros.

I too have a strong antipathy to macros. I don't reject them absolutely,
but they need a very good justification. I can't see myself ever using
BOOST_FOREACH because the problem it is solving isn't hard enough to
warrant the obfuscation. Comparing:

    BOOST_FOREACH( int i, vec )
        cout << i;


    for (iterator i = vec.begin(); i != vec.end(); ++i)
        cout << *i;

the macro just doesn't seem worth it.

I find it scary. When I look at the implementation I am not reassured.
This is replacing something I understand with something I frankly don't.

I have looked at the documentation and found it a bit superficial. For
example, I can't tell whether the example above is actually supported. All
the examples in the documentation have braces around the loop body: are
those just the author's preferred style, or are they required by the
macro? I looked at the implementation and I still can't tell. I prefer to
omit braces when they are not required.

I have not tried to use the macro. From the source, it looks like it
injects a largish number of local variables into the code, and these will
show up in the debugger and need to be understood to follow how the loop
is progressing.

For what it's worth, I think the design is impressive and if I had come up
with it I'd be very proud. Congratulations. The problem is that it is too
clever. It is using a sledgehammer to crack a nut.

I am not sure how one is supposed to vote in these circumstances - for a
proposed library that one wouldn't use oneself. I don't necessarily want
to prevent other people from using it if they want. I think it could help
demonstrate both the usefulness of type inference and how yucky type
inference is to achieve in C++ at present. It is an argument for language
change. However, I guess it doesn't need to be part of Boost to do that.

I vote against accepting BOOST_FOREACH into Boost. I hope the Review
Manager pays more attention to my reasons than my vote.

-- Dave Harris, Nottingham, UK.

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