Cantera version

2.5.0a3

Operating System

Any

When building from source, either Python 2 or Python 3 should be able to be used to run SCons. The new ck2yaml and cti2yaml scripts depend on Python 3 features. The build script relies on at least ck2yaml to convert CHEMKIN input files to the YAML format, so builds that use Python 2 to run SCons and don't specify a python_cmd that is a Python 3 executable result in errors. One of them is documented on the Google Group:

scons: Building targets ...
"/usr/bin/python" interfaces/cython/cantera/ck2yaml.py --quiet --no-validate --input=data/inputs/gri30.inp --output=build/data/gri30.yaml --transport=data/transport/gri30_tran.dat
  File "interfaces/cython/cantera/ck2yaml.py", line 177
    def __init__(self, *, Tmin, Tmax, Tmid, low_coeffs, high_coeffs, note=''):
                        ^
SyntaxError: invalid syntax
scons: *** [build/data/gri30.yaml] Error 1
scons: building terminated because of errors.

Steps to reproduce

1. Run SCons with a Python 2 sys.executable and do not specify a Python 3 executable in python_cmd

One possible solution to this is to check the YAML files into the repository rather than creating them during the build process. Another option is to make the scripts compatible with Python 2.