In article <1eh3zee.158fxcogv41w4N%dwalker07@snet.net.invalid>,
dwalker07@snet.net.invalid (Daryle Walker) wrote:

| I was attempting to use a bitset (from <bitset>) as part of another
| class and I needed to look at bits from a constant object.  My function
| is set up so I know that the bit indices are correct.  To my shock, I
| found out that operator[] for bitset objects is non-const only, there is
| no const version!  (Josuttis' C++ Library book mistakenly believes that
| there is a const version.)  For now, my workaround is to use the "test"
| method, even though I now have the overhead of that method's (unneeded)
| index check.  (I could also pass a bitset object by value instead of
| constant reference.)
|
| Can this be fixed for the next standard (by defining a "template
| <std::size_t N> bool std::bitset<N>::operator[]( std::size_t pos )
| const")?

You might be interested in dr:

http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#11

-Howard

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"Howard Hinnant" <hinnant@anti-spam_metrowerks.com> wrote in message
> In article <1eh3zee.158fxcogv41w4N%dwalker07@snet.net.invalid>,
> dwalker07@snet.net.invalid (Daryle Walker) wrote:
>
> | I was attempting to use a bitset (from <bitset>) as part of another
> | class and I needed to look at bits from a constant object.  My function
> | is set up so I know that the bit indices are correct.  To my shock, I
> | found out that operator[] for bitset objects is non-const only, there is
> | no const version!  (Josuttis' C++ Library book mistakenly believes that
> | there is a const version.)  For now, my workaround is to use the "test"
> | method, even though I now have the overhead of that method's (unneeded)
> | index check.  (I could also pass a bitset object by value instead of
> | constant reference.)
> |
> | Can this be fixed for the next standard (by defining a "template
> | <std::size_t N> bool std::bitset<N>::operator[]( std::size_t pos )
> | const")?
>
> You might be interested in dr:
>
> http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#11
>
> -Howard

And what about similar operator in std::map? I understand, that operator []
can insert new values in map, but it is posible to forbid this (throw
exception or say that behavour is undefined if key can`t be found). I think
it is useful to make something like this:

const value_type &operator[] ( const key_type& x ) const;
Returns: find( x )->second;

Sergey


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I was attempting to use a bitset (from <bitset>) as part of another
class and I needed to look at bits from a constant object.  My function
is set up so I know that the bit indices are correct.  To my shock, I
found out that operator[] for bitset objects is non-const only, there is
no const version!  (Josuttis' C++ Library book mistakenly believes that
there is a const version.)  For now, my workaround is to use the "test"
method, even though I now have the overhead of that method's (unneeded)
index check.  (I could also pass a bitset object by value instead of
constant reference.)

Can this be fixed for the next standard (by defining a "template
<std::size_t N> bool std::bitset<N>::operator[]( std::size_t pos )
const")?

--
Daryle Walker
Mac, Internet, and Video Game Junkie
dwalker07 AT snet DOT net

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