@Xsecrets : Of course, it is not easy to implement, but the question is not about code complexity but about one essential feature.
The solution introduced here :
http://forum.opencart.com/viewtopic.php?f=24&t=22968 gives one good approach, perhaps the best.
Another approach could be to create a "flat" combination table as I done one several years ago for a fashion website.
It is not clean regarding relational DB, but it works well and fast.
With the classical tshirt example (option ID : logical name) :
1 : size
2 : color
3 : cut
...and some option values :
1 : M
2 : L
3 : XL
4 : red
5 : green
6 : slim
7 : T
8 : Marcel
Let's say the PHP script alsways takes (internaly) the options values regarding their ID rank.
The combination table could look like this :
product_id - options_value_ids - sku - stock - price
1 - 1,4,7 - 012 - 10 - 120.00
1 - 2,5,8 - 014 - 5 - 100.00
To link an option to another, we need another table :
id_combination - option_ids
1 - 1,2,3
And to finish, on the backend, a matrix of all combinations that lets the user fill in the linked data (SKU, stock, price, whatelse..)
That's not the best approach, but it is not the ugliest one and it could resolve the problem.
Anyway, it could be nice to have the Daniel's point of view.
To finish, I fully agree that dependant options will need to hack the core alot (or to implement it through vQMod, I did'nt tested it, so I can't say anything about it), but truely, even some users have not the need of such a feature and are saying it is just "nice to have", most of the other silent "testers" just have a look on Opencart and goes away because of the this missing feature.
Not convienced ? Try to implement a shop with OpenCart and to sell t-shirts, shoes, perfumes, furnitures...
If I took time to write this, it is because I feel that OpenCart could be a great solution, perhaps one of the best, with this simple feature...