@article{springer2017jip,
  author = {Matthias Springer and Hidehiko Masuhara and Robert Hirschfeld},
  title = {A Layer-based Approach to Hierarchical Dynamically-scoped Open Classes},
  pdf = {jip2017.pdf},
  journal = {Journal of Information Processing},
  year = 2017,
  volume = {25},
  optnumber = { },
  pages = {296-307},
  month = mar,
  doi = {10.2197/ipsjjip.25.296},
  annote = {Revised version of \cite{springer2016pro}, received 2016-07-08, accepted 2016-10-26},
  note = {Also published in IPSJ Transactions on Programming.},
  keywords = {Squeak, Smalltalk},
  abstract = {Open classes are frequently used in programming languages such as Ruby and Smalltalk to add or change methods of a class that is defined in the same component or in a different one. They are typically used for bug fixing, multi-dimensional separation of concerns, or to modularly add new operations to an existing class. However, they suffer from modularity issues if globally visible: Other components using the same classes are then affected by their modifications. This work presents Extension Classes, a hierarchical approach for dynamically scoping such modifications in Ruby, built on top of ideas from Context-oriented Programming (COP). Our mechanism organizes modifications in classes and allows programmers to define their scope according to a class nesting hierarchy and based on whether programmers regard an affected class as a black box or not. Moreover, Extension Classes support modularizing modifications as mixins, such that they can be reused in other components.}
}