Questions tagged [covariance]
Covariance, contravariance and invariance describe how the existing type inheritance hierarchy changes when subjected to some transformation (such as usage within generics). If the transformation keeps the ordering of the original hierarchy, it is "covariant". If it reverses it, it is "contravariant". If it breaks it, it is "invariant".
1
question
5
votes
3
answers
3k
views
"fake" covariance in PHP type-hinting
Here's the situation: I've got several distinct objects, each with their own responsability and (therefore) each their own dependencies. As this is code that will be implemented in 2 existing ...
- 10.9k