At 21:53 13/02/2004, you wrote:
Mat Marcus wrote:
<snip>
(while compiling monad3.cpp) monad3.cpp:82: error: no type named `second_type' in `struct OutputMonad<std::string>' This is a template shadow parameter issue, related to the fact that OutputMonad<> defines an inner type called "M", but a template member functions uses M as template parameter as well:
struct A { typedef int M;
template <class M> //* void foo(void) { M m; // which M is this? } };
I know the C++ committe is discussing this issue at this moment. The argument would be that "M" names the typedef because it's "more stable" than the template parameter (which could get renamed in an out-of-class definition). See also http://gcc.gnu.org/PR13967 for a detailed discussion. It's possible that GCC will emit a warning about this borderline case of shadowing, one day. This is worked around easily, by renaming the innest template parameter, in line 107 and 110, and all its subsequent uses.
I can't believe that??? So for int i = 12; { int i = 123; //* std::cout << i; } should I expect an output of 12 because the other i is more stable? Maybe I'm wrong, but it seems stupid to have one rule for one case, and a different rule for the effectively the same case. The sensible opinion seems that the lines marked //* take precedence, albeit ideally with a warning. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.573 / Virus Database: 363 - Release Date: 28/01/2004