On Sat, Oct 1, 2016 at 9:39 PM, Christian Tismer <tis...@stackless.com> wrote: > The exec() script inherited the __future__ statement! > It behaved like the future statement were implicitly there. > > Is that a bug or a feature?
It's documented, but not very noisily. https://docs.python.org/2/reference/simple_stmts.html#future-statements So if you want to isolate the execution environments, you can use compile() explicitly. Without isolation: Python 2.7.12+ (default, Sep 1 2016, 20:27:38) [GCC 6.2.0 20160822] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> exec(compile("print('hello','world')", "-", "exec")) ('hello', 'world') >>> exec(compile("from __future__ import print_function; >>> print('hello','world')", "-", "exec")) hello world >>> from __future__ import print_function >>> exec(compile("print('hello','world')", "-", "exec")) hello world >>> exec(compile("from __future__ import print_function; >>> print('hello','world')", "-", "exec")) hello world With isolation: >>> exec(compile("print('hello','world')", "-", "exec", 0, 1)) ('hello', 'world') >>> exec(compile("from __future__ import print_function; >>> print('hello','world')", "-", "exec", 0, 1)) hello world So I'd call it a feature, but possibly one that warrants a mention in the exec and eval docs. Maybe something like: https://docs.python.org/2/reference/simple_stmts.html#the-exec-statement [2] When strings are executed, __future__ directives active in the surrounding context will be active for the compiled code also. If this is not desired, see the compile() function's dont_inherit parameter. Would that clarify? ChrisA _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
