  The objective of this research is to analyse the ways members of open-source
software communities participate in design. In particular we focus on how users
of an Open Source (OS) programming language (Python) participate in adding new
functionalities to the language. Indeed, in the OS communities, users are
highly skilled in computer sciences; they do not correspond to the common
representation of end-users and can potentially participate to the design
process. Our study characterizes the Python galaxy and analyses a formal
process to introduce new functionalities to the language called Python
Enhancement Proposal (PEP) from the idea of language evolution to the PEP
implementation. The analysis of a particular pushed-by-users PEP from one
application domain community (financial), shows: that the design process is
distributed and specialized between online and physical interactions spaces;
and there are some cross participants between users and developers communities
which may reveal boundary spanners roles.
