I'm no expert on these type of libraries but I have come to the point where
I must find time to study *this* library more.
I have a current project that requires some re-writes in specific areas and
I'm hoping Boost will be able to make this job easier.
Is there something in boost that will ease the implementation of a
state-machine type functor.
As an example, I am using a 3rd party C++Builder component that makes socket
connections to hardware devices. I need to modify the connection code so
'what needs to be done after a connection success/failure' is handled in the
appropriate events. The thing is, this connection event can be called due
to connections in other areas of the application under different conditions.
If I can implement a state based connection handler then I could re-direct
the calls to the appropriate (alternate) event.
As an example (I'm only just starting to read up on the STL), I know I could
use a std::map to hold state values as the key and call the appropriate
handler via a pointer to a function in .second - what I'm hoping is there is
a library that allows for unrestricted function signatures (different
parameter lists) to be associated with state values.
To make this clearer
// I know this is not valid code but it explains what I'm after
typedef std::map
I'm no expert on these type of libraries but I have come to the point where I must find time to study *this* library more.
I have a current project that requires some re-writes in specific areas and I'm hoping Boost will be able to make this job easier.
Is there something in boost that will ease the implementation of a state-machine type functor.
As an example, I am using a 3rd party C++Builder component that makes socket connections to hardware devices. I need to modify the connection code so 'what needs to be done after a connection success/failure' is handled in
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 ?
--
Malcolm Smith
MJ Freelancing- http://www.mjfreelancing.com
Software Protection for C++Builder
Borland Technology Partner
"Malcolm Smith"
appropriate events. The thing is, this connection event can be called due to connections in other areas of the application under different conditions.
If I can implement a state based connection handler then I could re-direct the calls to the appropriate (alternate) event.
As an example (I'm only just starting to read up on the STL), I know I could use a std::map to hold state values as the key and call the appropriate handler via a pointer to a function in .second - what I'm hoping is there is a library that allows for unrestricted function signatures (different parameter lists) to be associated with state values.
To make this clearer
// 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;
Does this make sense to anyone ? I've probably got all the terminology wrong so feel free to correct me where ever applicable.
Thanks in advance.
-- Malcolm Smith MJ Freelancing- http://www.mjfreelancing.com Software Protection for C++Builder Borland Technology Partner
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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
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"
"Boost way" to do this that I know of.
Doug
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participants (2)
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Douglas Gregor
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Malcolm Smith