Re: Re: Which doorway

On Tuesday 10 December 2002 04:48 am, Malcolm Smith wrote:

...

I read Boost.Function info and it sounds like part of the solution.

Is there a way of associating a key with a container of *different* boost.Function's ?

Not directly. How are you planning to invoke functions in this map? You gave the example:

// I know this is not valid code but it explains what I'm after typedef std::map StateFunctions;

void Method1(void); int Method2(TCustomClass &MyClass);

StateFunctions[1] = Method1; StateFunctions[2] = Method2;

My question is: do you really want the parameter lists to be different for StateFunctions[1] and StateFunctions[2], meaning that when calling you might need something like:

foo = StateFunctions[x]; if (foo has arity zero) foo(); else if (foo has arity one with type TCustomClass) foo(herClass); else if (...) etc. etc.

?

Or are all the parameters to the functors known when they are put into the StateFunctions map? Then what you really want is something that achieves

desired effect:

StateFunctions[1] = Method1; StateFunctions[2] = something that calls Method2 with parameter herClass

If it's the latter case, you've run into the classic Boost.Bind/Boost.Function (or Boost.Lambda/Boost.Function, if your compiler can handle it) scenario :)

Then you want:

typedef std::map > StateFunctions;

StateFunctions[1] = &Method1; StateFunctions[2] = boost::bind(&Method2, boost::ref(&herClass));

int x = something(); StateFunctions[x](); // call the appropriate state function

If it's the former case (different parameter lists), then there's no

Doug, I think I can deal with the latter, I'll read boost.bind now and see if it fits the bill. If worst comes to worst I could always create a polymorphic 'payload' to go with the state information. Speed is not an issue so I'm not worried about the overheads. The functions being called send socket requests to a digital video recorder over a WAN and they take longer to perform than my app would ever perform. Thanks for the info....more reading. -- Malcolm Smith MJ Freelancing- http://www.mjfreelancing.com Software Protection for C++Builder Borland Technology Partner "Douglas Gregor" wrote in message news:200212100856.34752.gregod@cs.rpi.edu... the direct

"Boost way" to do this that I know of.

Doug

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