[Python-ideas] Proposal: Moratorium on Python language changes

Sturla Molden sturla at molden.no
Wed Oct 21 22:37:38 CEST 2009

Guido van Rossum skrev:
> I propose a moratorium on language changes. This would be a period of
> several years during which no changes to Python's grammar or language
> semantics will be accepted. The reason is that frequent changes to the
> language cause pain for implementors of alternate implementations
> (Jython, IronPython, PyPy, and others probably already in the wings)
> at little or no benefit to the average user
Isn't this the same as saying it is time to produce an industry standard 
(as in ISO, ECMA, ANSI, IEEE) for the Python language? ISO 
standardization of C++ has not prevented GNU, Borland, Microsoft, and 
others to implement proprietary language extensions in their C++ 
compilers. But if we stick to writing standard C++, it will compile on 
standard compliant C++ compilers from any vendor. As I see it, the 
problem is not "language changes", but one implementation (CPython) 
being the "de facto" Python language standard. Maybe there should be a 
real Python standard? A syntax change in CPython would be a CPython 
specific language extension (like GNU extensions to C), not a language 
change. Today, a syntax change in CPython is a redefinition of the 
Python language. That will be avoided with a standard.

Cython (and Pyrex before) adds many extensions to the Python language, 
while aiming at being compliant with "pure Python". But what is "pure 
Python" anyway? It would be much easier for everyone if there was a 
piece of paper defining the Python language -- and possibly certain 
critical parts of the standard library.

Also, an industry standard for the Python language would help adoption 
of Python in many organizations. Except for Java, only standardized 
languages tend to be considered for large projects. Many has strict 
policies of only using standardized languages to ensure availability of 
compilers/interpreters in the future.

Personally I think Python 3000 is mature enough for a standard.

Sturla Molden

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