Functions with lots of inputs in python

why.py

"""
Weird stuff happens when you define python functions with lots of inputs
"""
from subprocess import check_call


def make_file(N=500, out='tmp.py'):
    args = ['a_%i' % i for i in range(N)]

    with open(out, 'w') as outfile:
        outfile.write('N=%i\n' % N)
        outfile.write('def s(%s)' % (','.join(args)))
        outfile.write(':\n')
        outfile.write('    return %s' % ('+'.join(args)))


def test_py2(N):
    make_file(N)
    check_call(['python', '-c' 'from tmp import N, s; args = list(range(N)); s(*args)'])


def test_py3(N):
    make_file(N)
    check_call(['python3', '-c' 'from tmp import N, s; args = list(range(N)); s(*args)'])


for N in [100,     # ok on py2/3
          200,     # ok on py2/3
          500,     # ok on py2, syntax error on py3
          10000,   # ok on py2, syntax error on py3
          1000000,  # prone to segfault on py2, syntax error on py3
          ]:
    print "\n\n\nMaking function with %i arguments" % N
    try:
        test_py2(N)
        print '    Python 2 OK'
    except Exception as e:
        print '    Python 2 Failed'
        print(e)

    try:
        test_py3(N)
        print '    Pytho 3 OK'
    except Exception as e:
        print '    Python 3 Failed'
        print(e)