@InProceedings{bessai_et_al:LIPIcs.ECOOP.2021.4,
  author =	{Bessai, Jan and Heineman, George T. and D\"{u}dder, Boris},
  title =	{{Covariant Conversions (CoCo): A Design Pattern for Type-Safe Modular Software Evolution in Object-Oriented Systems}},
  booktitle =	{35th European Conference on Object-Oriented Programming (ECOOP 2021)},
  pages =	{4:1--4:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-190-0},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{194},
  editor =	{M{\o}ller, Anders and Sridharan, Manu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2021.4},
  URN =		{urn:nbn:de:0030-drops-140476},
  doi =		{10.4230/LIPIcs.ECOOP.2021.4},
  annote =	{Keywords: Expression problem, software evolution, type safety, producer method, binary method}
}