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From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-06-26 14:23:31

From: "Joerg Walter" <jhr.walter_at_[hidden]>

> > I think I'd much prefer using expression
> > templates always, even in (otherwise) debug builds...
> Why? AFAIK using expression templates in debug builds increases compile
> times and object file size (but I'll recheck that).

Because the semantics could change in some cases, e.g.:

    x = f(a + b + c);

If f is a function template, the deduced argument type will be different
when ETs are enabled, which could have consequences that are
hard-to-predict. I do nearly all of my testing against debug builds, and I
don't want to be surprised when I switch to release. I trust the compiler
to preserve semantics when I change optimization settings, but getting an
expression instead of a matrix in some generic function might be too big a
jump for me to tolerate.

Just personal preference; I have no problems with the defaults you chose,
though I would like it if you would issue a suitable warning about the
pitfalls in the documentation.


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