Re: [cgi-devel] [Cgi-devel] request const access

[Darren G. <lis...@go...>]

Hi Richard,

On 6 July 2010 12:13, Richard Forrest <ri...@th...> wrote:

>
> Thanks for responding so quickly to my bug report yesterday.
>

Sorry about the slowness of this one! Apparently it slipped through my
inbox.


> Today I have a const correctness problem.
>
> I have a 'request' object that has been passed by const reference and
> would like to query the contents of its get, session etc.
>
> 1. data_map_proxy::count(const key_type&) is not a const member
> function. Is there any reason for that? I tried changing it to const
> without any obvious problems.
>

No reason. I've changed this to const locally.


> 2. I can use pick() to access 'get' parameters but it does not seem to
> work for 'session' parameters. Is there any way to access session
> parameters in a const context?
>

The session data doesn't have pick(), but should be accessible in a const
context. Are you able to post a short test case please?

I've wondered about this inconsistency before, but decided against "fleshing
out" the session to have the same members as the other request data. The
basic_session<> class template is as slim as possible since the idea is that
library users can customise it. The class itself is little more than:

template<typename T>
class basic_session : public T, noncopyable
{
    // getter / setter for the session id.
    string const& id() const;
    void id(string const&);

    // check / set if the session is loaded.
    bool loaded() const;
    void loaded(bool);
};

The only reason count(), et al. exist is that T defaults to
std::map<string,string>. One option that is possible is to default T to a
wrapper over std::map<> that adds the pick(), etc. members.

Thoughts?

Cheers,
Darren