Re: We do not use C++ exceptions

From:
Le Chaud Lapin <jaibuduvin@gmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Wed, 21 Jan 2009 12:54:49 CST
Message-ID:
<7aa5a205-931b-419b-a7fc-a6af843cad2b@n41g2000yqh.googlegroups.com>
On Jan 14, 12:37 pm, Mathias Gaunard <loufo...@gmail.com> wrote:

On 14 jan, 01:19, Le Chaud Lapin <jaibudu...@gmail.com> wrote:

Here is example of big-integer division code that could be buried deep
within a cryptographic operation:

Integer operator / (const Integer &dividend, const Integer &divisor)
{
   Integer quotient, remainder;
   if (!Integer::divide (dividend, divisor, quotient, remainder))
     throw Integer::DIVISION_BY_ZERO;
    return quotient;

}

Integer::divide() returns true for success, false for failure, but
operator / would lose all its beauty if it had to return an error:


Why not throw directly from Integer::divide?
You could also return a tuple (here, a pair) rather than taking
objects to modify by reference.

This would likely result in more efficient code, for a number of
reasons.


Hmm...I thought I had a reason, but after checking and rechecking my
Integer.cpp file, I cannot find one, so thanks...I will do just
that. :)

For example,
millions, if not billions, of lines of C++ have been written, and we
still do not have obviously fundamental classes like hierarchies and
associative hierarchies.


A recursive variant might provide the kind of thing you're looking
for. See Boost.Variant.
This is usually how trees are handled in high-level languages, be it
functional ones (where the variant is explicit) or dynamic ones (where
the variant is implicit, it's the dynamic typing).


I have several templated hierarchy classes, with operations and O(n)
that one would reasonable expect: not spectactular, but O[log(n)]
where it matters.

Property trees are also a nice way to deal with trees. (You associate
a path in a tree with a value, quite useful for hierarchical
configuration files)
You might want to look at Boost.PropertyTree.


That would be...

typedef Associative_Monarchy<String<>, Associative_Set<String<>,
String<> > > PropertyTree;
PropertyTree::Path path;

.... in the my model.

I agree that one can get very close to XML-like internal data
structures very quickly with these types of containers.

And the reachability provide by combining such primitives, along with
the regular list<>, set<>, map<>, etc., is staggering.

-Le Chaud Lapin-

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