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From: Dave Steffen (dgsteffen_at_[hidden])
Date: 2005-11-11 10:59:56

Boris Burger writes:
> Hello,
> the issue with extra semicolons at namespace or class scope is
> surely nothing new and has been discussed extensively.

 Yes, I was one of the instigators...

> Still, I am not able to handle its incarnation in ptr_container
> sources, with G++ 3.4.5 (-ansi -pedantic). It goes like this:
> In ptr_map_adapter.hpp (and elsewhere), definition of class template
> ptr_map_adapter_base contains:
> ptr_map_adapter_base, base_type );
> at class scope. G++ 3.4.5 reports the extra semicolon as
> an error (-ansi -pedantic warning level is rather strict here).

 ... because I was porting our code to GCC 3.4. (More accurately, I
 was porting our code to 3.4 with the errors and warnings turned all
 the way up.)

> Due to our company's policy lowering the warning levels is not an
> option. Patching the ptr_container classes would do the trick
> but that would require rather painful process of going through
> the Boost sources with each new version and removing extra
> semicolons.

 In fact, I don't think there's a way to lower warning levels to
 _just_ get rid of the semicolon complaints; you'd also be turning off
 warnings you want. The only solution I found was to either

          A) remove the semicolon, or
          B) to use a macro definition

 A) is easiest, but may make people's editors unhappy.

 B) involves something that is either clever, or a bletcherous hack,
 or both. I've found that things like:

   namespace empty_namespace_for_semicolons {
    void allow_semicolon(); }

   typedef int semicolon_allowed_after_this_typedef

 namespace only_for_semicolon=empty_namespace_for_semicolons

  using empty_namespace_for_semicolons::allow_semicolon

 do the trick; these were suggested by people on this list. You'd then
 do something like

          a,b ) ALLOW_SEMICOLON1

 And, finally, write your code like this:

      ptr_map_adapter_base, base_type );

 Clever? Or bletcherous hack? I think both. :-)

Dave Steffen, Ph.D. On a paper submitted by a physicist colleague:
Software Engineer IV
Numerica Corporation "This isn't right. This isn't even wrong."
ph (970) 419-8343 x27
fax (970) 223-6797 -- Wolfgang Pauli
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