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< Erlang ~ State handling with module inhertance |
| flodis |
 Posted: Sat Oct 31, 2009 3:46 pm |
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User
Joined: 09 Jul 2008
Posts: 27
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I am having some thoughts how implement an easy state management with module inheritance.
I have these modules:
obj.erl
living.erl
animal.erl
player.erl
Each of them -extends() the lower module in a natural order.
My problem is how to best handle state, each object type has its own state, but the lower object only operates on their own state. For example when accessing a function in animal it wants the animal state, not the player state.
This gives me the obvious problem that I have to extract the correct state, which makes the code messy and impossible to maintain.
Adding a function to the obj.erl would require updates in all other objects.
I thought of using a generic state of all objects, and store type specific data in the process dictionary.
Is there anyone with an alternative solution for my problem? |
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| Allan |
| Posted: Sun Nov 01, 2009 9:30 am |
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User
Joined: 29 Jun 2009
Posts: 30
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flodis wrote: My problem is how to best handle state, each object type has its own state, but the lower object only operates on their own state. For example when accessing a function in animal it wants the animal state, not the player state.
Use something like [{atom(), term()}] to store all the data of an "object". Then it is easy to add new properties as needed. animal:is_alive/1 will simply access the {'is_alive', boolean()} entry in the given properties list - and player:get_level/1 may use the {'pc_level', integer()} entry from the given property list.
flodis wrote: I thought of using a generic state of all objects, and store type specific data in the process dictionary.
Is there anyone with an alternative solution for my problem?
Do not abuse the process dictionary!
Better use ETS, gen_server processes, or something similiar for storing the object states. Static ("class") properties that are equal for all "instances" of a type (such as animal or player) can be stored there too. |
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