[Boost-users] [enable_if] Why any other than lazy?

From: Robert Jones (robertgbjones_at_[hidden])
Date: 2008-08-08 17:01:53

Boost.EnableIf defines enable_if etc, and goes on to define lazy_enable_if,
which
the documentation states is for the circumstances and compilers when the
non-lazy
version would break since the instantiation for which SFINAE should apply is
a nested
instantiation which is not properly processed by some compilers.

What I don't understand is why anyone would wish to use the non-lazy
versions,
since AFAICS the lazy version will always work.

Then the obvious question is why the non-lazy versions exist at all?

Thanks, Rob.

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