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Subject: [ggl] Surprising ADL
From: Bruno Lalande (bruno.lalande)
Date: 2010-05-07 09:07:58

Hi ZhouShuangJiang,

> Talking of ADL, I also found some part of the lib use qualified call to
> stdlib functions, which will forbid the use of ADL.
> For example, in
> boost::geometry::detail::overlay::enrich_containment::enrich(), the
> qualified std::abs() will forbid the user from using his own abs() for UDT.

Good catch, we indeed have to remove all those qualified calls to enable ADL.

> Furthermore, I am not so clear about what kind of UDT can be used as
> coordinate type. From my point of view, it seems the lib suppose the
> standard arithmetic operations are supported for all the built-in
> type(especially, floating point types). And the UDT is based on such
> assumption. For example, if user uses some fixed point type as coordinate
> type, and expects the lib to act upon the fixed point arithmetic(coming with
> the fixed point type), he will not get what he wants(e.g., distance
> algorithm won't compile, since there is no proper result type).

The plan is to accept as a coordinate type any type which is
compatible with the Boost.Math bindings, which provides wrappers
around 3rd party numeric types to enable their use with ADL and usual
arithmetic operators.


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