Korcan, Regarding visitation for boost::any, I did some work a long while ago in the Boost Sandbox: http://boost-sandbox.cvs.sourceforge.net/boost-sandbox/boost-sandbox/boost/a... http://boost-sandbox.cvs.sourceforge.net/boost-sandbox/boost-sandbox/boost/v... I haven't looked at any of this in a while though. Also, in case you are interested, there is the more experimental application of visitation in the form of a "switch" construct: http://boost-sandbox.cvs.sourceforge.net/boost-sandbox/boost-sandbox/boost/t... Eric Korcan Hussein wrote:
I propose 3 changes/additions made to boost::any:
1. Support for custom allocator types.
2. Support for in-place factories.
3. Last but not least boost::variant style visitors.
I'll elaborate on the last one, i've written primarily support for boost::variant style visitors for boost::any. The method is based on the acyclic visitor pattern and works as follows:
struct printer_fn : boost::dynamic_visitor<int, std::string> {
void operator()(int) const { std::cout << "int\n" } void operator(const std::string&) cosnt { std::cout << "string\n" }
} const printer;
......
boost::any a = 1;
boost::apply_visitor(a, printer);
a = std::string();
boost::apply_visitor(a, printer);
I'm looking to also provide the ability to extend their visitors (and override if need be) to support more types as well as provide "catch-all" (i.e (const) boost::any&) implementation which defaults to throwing an exception. I also want this to be constant-correct in the way of const_iterator and iterator, i need to look into this carefully since there are 4-cases to deal with (instead of 2).
Is there any interest for these changes/additions?
Thanks. Korcan Hussein.
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