Programming Forums > Application Development > C++

l2u · Jul 16th, 2007, 5:05 PM

Hello

I have a programming design question..
Lets say I have 3 classes like below:

class parser {
};

class user {
};

class session {
public:
	std::list<user> m_list;
};

Session class is a 'main class' where most of the work is being done (in loop/s)..
It has a list of user objects, where each user needs access to 1 particular parser object (parser class).

I dont want each user to have its own parser object since that would be unneccessary..

I wonder what is the best approach to make class user (user objects) be able to access data in one parser object?
I know most of you would just pass parser object's reference to user class constructor, and then access data this way.

Is there any better way/design pattern to achieve that?
Maybe I shouldn't bother because this might be the best/easiest way?
Or is there more 'professional' way?

Another thing I'm unsure about..

In case passing reference of parser object to user objects is the best way, where would you guys define parser object?

Does this seem okay:

(Toggle Plain Text)

class session {
public:
	std::list<user> m_list;
	parser m_parser;
};

Thanks for help
Regards

DaWei · Jul 16th, 2007, 6:55 PM

Why don't you make a parser object a member of a user object?

lectricpharaoh · Jul 16th, 2007, 8:03 PM

Dunno if it fits with your design requirements, but have you considered making parser a static class?

l2u · Jul 17th, 2007, 4:07 PM

Quote:

Originally Posted by DaWei

Why don't you make a parser object a member of a user object?

This would take too much memory. parser class has some data that doesnt need to be multiplied and it has only one function that is being called with different arguments.

Quote:

Originally Posted by lectricpharaoh

Dunno if it fits with your design requirements, but have you considered making parser a static class?

How should I construct parser object in class when its static? The usual way?

(Toggle Plain Text)

class user {
public:
user(int somedata) : m_parser(somedata) { } 
static class parser m_parser;
};

grumpy · Jul 17th, 2007, 5:54 PM

Quote:

Originally Posted by l2u

This would take too much memory. parser class has some data that doesnt need to be multiplied and it has only one function that is being called with different arguments.

In that case, there is no need for your parser to be a class at all. It would be better implemented as a single function that is called, with arguments providing necessary data, by your user classes.

l2u · Jul 17th, 2007, 9:44 PM

Quote:

Originally Posted by grumpy

In that case, there is no need for your parser to be a class at all. It would be better implemented as a single function that is called, with arguments providing necessary data, by your user classes.

Class itself still holds some data that is needed by parser class.
And I dont like having global objects/functions.

DaWei · Jul 17th, 2007, 10:20 PM

You seem to have all the answers. One wonders why there is a question.

lectricpharaoh · Jul 17th, 2007, 11:26 PM

Quote:

Originally Posted by l2u

How should I construct parser object in class when its static? The usual way?

My bad; that was a brain fart. I should have said 'a class whose public methods are all static', as that is more accurately what I meant.

That way, you group one or more functions into your class, and can call them like regular global functions. The class can have an internal state, such that it can initialize itself when the first method is called, or upon calling some initialization method (for example, to 'attach' the stream std::cin as the source for user input).

grumpy · Jul 18th, 2007, 6:23 AM

Quote:

Originally Posted by l2u

Class itself still holds some data that is needed by parser class.

Not a valid justification for using a class rather than a single function. Simply pass the needed data as an argument (eg a struct, a pointer to a struct, a reference to a struct) to the function.

Quote:

Originally Posted by l2u

And I dont like having global objects/functions.

Lots of people don't like eating vegetables either. But people who eat vegetables are usually healthier than those who don't.

Jul 16th, 2007, 5:05 PM	#1
l2u Newbie Join Date: Mar 2007 Posts: 24 Rep Power: 0	programming design Hello I have a programming design question.. Lets say I have 3 classes like below: (Toggle Plain Text) class parser { }; class user { }; class session { public: std::list<user> m_list; }; class parser { }; class user { }; class session { public: std::list<user> m_list; }; Session class is a 'main class' where most of the work is being done (in loop/s).. It has a list of user objects, where each user needs access to 1 particular parser object (parser class). I dont want each user to have its own parser object since that would be unneccessary.. I wonder what is the best approach to make class user (user objects) be able to access data in one parser object? I know most of you would just pass parser object's reference to user class constructor, and then access data this way. Is there any better way/design pattern to achieve that? Maybe I shouldn't bother because this might be the best/easiest way? Or is there more 'professional' way? Another thing I'm unsure about.. In case passing reference of parser object to user objects is the best way, where would you guys define parser object? Does this seem okay: (Toggle Plain Text) class session { public: std::list<user> m_list; parser m_parser; }; class session { public: std::list<user> m_list; parser m_parser; }; Thanks for help Regards

Jul 16th, 2007, 6:55 PM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Why don't you make a parser object a member of a user object? __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jul 16th, 2007, 8:03 PM	#3
lectricpharaoh Caffeinated Neural Net Join Date: Jun 2005 Location: Wet west coast of Canada Posts: 1,126 Rep Power: 5	Dunno if it fits with your design requirements, but have you considered making parser a static class? __________________ And once again, Probability proves itself willing to sneak into a back alley and service Drama as would a copper-piece harlot. - Vaarsuvius, Order of the Stick

Jul 17th, 2007, 10:20 PM	#7
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	You seem to have all the answers. One wonders why there is a question. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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