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Generic Container

Skyler York · 2002-09-17T03:20:19

What I''m looking for is a container that can hold any type of data. However, unlike a vector, list, and other templated containers, I need it to hold all the different types of data at once. And it needs to be type-safe The first idea that came to my head was that this container class would actually wrap a vector (or actually be templated itself to accept what type of container to wrap) and use this to hold a list of pointers. The pointers would point to a base object, from which all other object types will be derived. However, I don''t want to implement a custom derived class everytime we have a new object type we wish to maintain. I want these derived classes to be templated so that we can pass the different types "on-the-fly" (via a templated function). These derived classes would wrap an instance of that type and contain simple Set and Get functions. My problems arise when I want to access these objects from the base class pointer I''m storing. I can''t have any virtual functions in the base class, because the derived classes actually use templated functions and variables. I can''t template the base class, because then I don''t have any method of storing a generic pointer to any type. My only solution would be to downcast from the base pointer to the derived class type and call a function, but now it isn''t type-safe. Am I completely missing something or is this more complicated than it looks? Technically I could implement the whole thing without templates or type-safety and make it "dirty", but I don''t want to do that. Hopefully I''m not completely off base here

General and Gameplay Programming Programming

Started by Zipster September 14, 2002 11:43 PM

21 comments, last by Zipster 21 years, 7 months ago

Zipster

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September 17, 2002 01:34 AM

I'm sorry, I did read your post, but just completely forgot to reply to it

Sorry again...

Anyway, your solution sounds like it would work pretty good. A few questions though. How exactly are you overloading your functions and operators in your derived templated classes? To use the pure virtual Read function from the Attribute* class, you can't overload return types or parameter types (at least I don't think)... so how is the correct type set via the = operator (that's where I'm assuming it converts the Mem1FromFile Attribute* pointer to the correct value type to store in member1)?

I'm just confused how you are overloading these things, as in the pure virtual base class you pretty much have to have the types filled in, namely for the Read function, right? This whole construct is what I was trying to get at from my original thought all the way in post 1, but I couldn't figure out how to go about setting this up.

[edited by - Zipster on September 17, 2002 2:36:28 AM]

Fruny

1,658

September 17, 2002 03:02 AM

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." — Brian W. Kernighan

Zipster

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September 17, 2002 03:20 AM

That''s the thing, I don''t need a full reimplementation of it - that and I doubt I''d be able to understand what the heck was going on in the boost::any code besides