RE: [boost] Variant (aka Discriminated Union) implementation

From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2002-06-25 06:32:52

Giovanni Bajo wrote:
> I tried compiling your library with Comeau 4.3.0.
> 
> Visitor.hpp misses a typename on line 156 (for 
> select_if_c<>::type). Then,
> the compilation of variant_test dies with this error:
> 
> "d:\boost_1_28_0\boost/mpl/lambda.hpp", line 129: error: the 
> type of partial
>           specialization template parameter template template 
> parameter "F"
>           depends on another template parameter
>   BOOST_PP_REPEAT_2ND(
>   ^
> 
> Now, since lambda.hpp, for a dummy like me, is just as 
> readable as Hungarian (no offense intended, for either), 

I suppose you meant "Russian" :).

> I don't have the faintest idea about what's going on.

MPL's lambda test file (boost/libs/mpl/test/lambda.cpp) compiles perfectly
fine on my machine (Comeau C/C++ 4.3.0 BETA#4 for Windows, strict mode
(--A), with the latest sources from CVS/mpl_v2). Actually, besides the
errors you've reported, a couple more missing typenames, and an error in
variant's own version of "mpl/for_each.hpp" header the whole
"variant_test.cpp" compiles fine as well. Must be a configuration error or
something.

> Variant_test takes about 5 minutes to compile. 

Not anymore :). That was because I wasn't as agile as you in switching to
the new version of the compiler :). I bumped up the __EDG_VERSION__ check in
"mpl/aux_/config/use_preprocessed.hpp", and now everything should work
_much_ faster - check out the CVS (it takes ~15 secs to compile
"variant_test.cpp" on my machine). 

Aleksey