Best way to avoid a thousand if statements?

Question

I basically have this problem: right now, we have a system where it gets a string as input, and it basically says ACTION:.

For each of the actions there is an automatically generated function(Rational Rose GRRR), such as

bouncer_comm.chatMessage("data goes here").sendAt(msg->sapIndex0());
bouncer_comm.askforname().sendAt(msg->sapindex0());

bouncer_comm returns an RTOutSignal, I can't create them manually because of the bizarre structure rose uses.

Right now, my only option is to create a hundred or so if statements, where I do:

if(action == "CHAT")  bouncer_comm.chatMessage("data goes here").sendAt(msg->sapIndex0());

Which is realllllyy annoying.

What would be the best way to avoid this? I've looked at / tried countless things, this is a really old version of rational rose (pre 2k) and yeah.

If anyone has any ideas that would be amazing.

score 12 · Accepted Answer · answered Mar 21 '09 at 21:35

12

I like @cobbal's idea of the function pointer hash above, but you could replace this conditional logic with polymorphism.

see: http://c2.com/cgi/wiki?ReplaceConditionalWithPolymorphism

answered Mar 21 '09 at 21:35

killingmichael

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Polymorphism is probably best here, combined with a factory of some sort. Different commands mean a different Command subclass. – strager Mar 21 '09 at 21:43
Polymorphism is absolutely best, more idiomatically C++ – Dexygen Mar 21 '09 at 21:48

score 6 · Answer 2 · answered Mar 21 '09 at 21:27

6

A hash storing function pointers could work well here

answered Mar 21 '09 at 21:27

cobbal

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Could you perhaps care to elaborate? I tried making a map of function pointers but since they take different values it causes problems. – UberJumper Mar 21 '09 at 21:29
I'd agree if this were C and not C++, but since it's the latter, would have to favor the polymorphic approach – Dexygen Mar 21 '09 at 21:51
If each method has different signatures, avoiding function pointers is probably in your interest. – Robert P Mar 21 '09 at 21:53
To be honest, I know very little about boost. Sounds like these other suggestions will work better. – cobbal Mar 21 '09 at 22:01

Geo · Answer 3 · 2009-03-21T21:45:59.893

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I used polymorphism combined with the factory pattern. I reduced a lot of if's to this :


MyAbstractClass *ac = Factory::getHandlerFor(data);
ac->perform(parameters);

edited Mar 21 '09 at 21:45

answered Mar 21 '09 at 21:40

Geo

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score 1 · Answer 4 · answered Mar 21 '09 at 21:46

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I think the easiest is a map of boost::functions.

answered Mar 21 '09 at 21:46

rlbond

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Brian R. Bondy · Answer 5 · 2009-03-21T21:59:10.033

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You could use boost::bind or boost::function and a map. This would allow you to call the correct function, even know each function has a different amount of parameters.

If you don't want any extra code you could use function objects and inheritance.

edited Mar 21 '09 at 21:59

answered Mar 21 '09 at 21:39

Brian R. Bondy

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Best way to avoid a thousand if statements?

5 Answers5