namespace question

Discussion in 'Python' started by Elaine Jackson, Sep 2, 2004.

  1. I would like to be able to write a function f, which will live in a module M,
    and will call a function g, such that, when f is imported from M into the
    interpreter, and invoked there, its invokation of g will return the
    interpreter's global namespace. Is there a way to do this and, if so, how?
    Muchas gracias for any and all assistance.

    Peace
     
    Elaine Jackson, Sep 2, 2004
    #1
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  2. Elaine Jackson

    Phil Frost Guest

    I'm not sure I understand what you are asking, but maybe globals() is
    what you want?

    On Thu, Sep 02, 2004 at 01:52:46PM +0000, Elaine Jackson wrote:
    > I would like to be able to write a function f, which will live in a module M,
    > and will call a function g, such that, when f is imported from M into the
    > interpreter, and invoked there, its invokation of g will return the
    > interpreter's global namespace. Is there a way to do this and, if so, how?
    > Muchas gracias for any and all assistance.
    >
    > Peace
     
    Phil Frost, Sep 2, 2004
    #2
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  3. Elaine Jackson

    Peter Hansen Guest

    Elaine Jackson wrote:
    > I would like to be able to write a function f, which will live in a module M,
    > and will call a function g, such that, when f is imported from M into the
    > interpreter, and invoked there, its invokation of g will return the
    > interpreter's global namespace.


    What does that last part mean? There is no such thing as the
    "interpreter's global namespace". Each module is its own namespace.

    -Peter
     
    Peter Hansen, Sep 2, 2004
    #3
  4. By "the interpreter's global namespace" I mean the dictionary that gets returned
    if you evaluate 'globals()' in the interpreter.

    "Peter Hansen" <> wrote in message
    news:...
    | Elaine Jackson wrote:
    | > I would like to be able to write a function f, which will live in a module
    M,
    | > and will call a function g, such that, when f is imported from M into the
    | > interpreter, and invoked there, its invokation of g will return the
    | > interpreter's global namespace.
    |
    | What does that last part mean? There is no such thing as the
    | "interpreter's global namespace". Each module is its own namespace.
    |
    | -Peter
     
    Elaine Jackson, Sep 3, 2004
    #4
  5. It's what I want in the sense that it returns the correct dictionary when
    globals is invoked interactively. What I want is to have a function that can be
    imported into the interpreter and that will return that same dictionary.

    "Phil Frost" <> wrote in message
    news:...
    | I'm not sure I understand what you are asking, but maybe globals() is
    | what you want?
    |
    | On Thu, Sep 02, 2004 at 01:52:46PM +0000, Elaine Jackson wrote:
    | > I would like to be able to write a function f, which will live in a module
    M,
    | > and will call a function g, such that, when f is imported from M into the
    | > interpreter, and invoked there, its invokation of g will return the
    | > interpreter's global namespace. Is there a way to do this and, if so, how?
    | > Muchas gracias for any and all assistance.
    | >
    | > Peace
     
    Elaine Jackson, Sep 3, 2004
    #5
  6. Elaine Jackson <> wrote:

    > I would like to be able to write a function f, which will live in a module M,
    > and will call a function g, such that, when f is imported from M into the
    > interpreter, and invoked there, its invokation of g will return the
    > interpreter's global namespace. Is there a way to do this and, if so, how?
    > Muchas gracias for any and all assistance.


    There is no "interpreter global namespace". If you mean the namespace
    of the calling module (which could be the interactive session's __main__
    if that's who did the importing) you can get there via sys._getframe --
    it's meant for debugging purposes (note the leading underscore) but it
    will work. If you mean the namespace of __main__ (which could be the
    interactive session if there is one) you can get the __main__ module
    anywhere as sys.modules['__main__'] and a vars call around that will
    give the module's dictionary (which is, I assume, what you mean by
    namespace).


    Alex
     
    Alex Martelli, Sep 3, 2004
    #6
  7. Elaine Jackson

    Peter Hansen Guest

    Elaine Jackson wrote:

    > By "the interpreter's global namespace" I mean the dictionary that gets returned
    > if you evaluate 'globals()' in the interpreter.


    As Alex said then:

    (in module nstest.py):
    import __main__
    vars(__main__)['spam'] = 'baz'

    (in interactive session with extra spacing for readability):
    c:\>python
    >>> globals()

    {'__builtins__': <module '__builtin__' (built-in)>, '__name__':
    '__main__', '__doc__': None}

    >>> import nstest


    >>> dir()

    ['__builtins__', '__doc__', '__name__', 'nstest', 'spam']

    >>> globals()

    {'__builtins__': <module '__builtin__' (built-in)>, '__name__':
    '__main__', 'nstest': <module 'nstest' from 'nstest.py'>, '__doc__':
    None, 'spam': 'baz'}



    -Peter
     
    Peter Hansen, Sep 3, 2004
    #7
  8. Elaine Jackson <> wrote:

    > It's what I want in the sense that it returns the correct dictionary when
    > globals is invoked interactively. What I want is to have a function that
    > can be
    > imported into the interpreter and that will return that same dictionary.


    so what's wrong with:

    def main_dictionary():
    import __main__
    return vars(__main__)


    ???
     
    Alex Martelli, Sep 4, 2004
    #8
  9. On Fri, 3 Sep 2004 08:11:35 +0200, (Alex Martelli) wrote:

    >Elaine Jackson <> wrote:
    >
    >> I would like to be able to write a function f, which will live in a module M,
    >> and will call a function g, such that, when f is imported from M into the
    >> interpreter, and invoked there, its invokation of g will return the
    >> interpreter's global namespace. Is there a way to do this and, if so, how?
    >> Muchas gracias for any and all assistance.

    >
    >There is no "interpreter global namespace". If you mean the namespace
    >of the calling module (which could be the interactive session's __main__
    >if that's who did the importing) you can get there via sys._getframe --
    >it's meant for debugging purposes (note the leading underscore) but it
    >will work. If you mean the namespace of __main__ (which could be the
    >interactive session if there is one) you can get the __main__ module
    >anywhere as sys.modules['__main__'] and a vars call around that will
    >give the module's dictionary (which is, I assume, what you mean by
    >namespace).
    >

    This brings up the question of standard terminology (e.g. for namespace).
    If one googles for python glossary, the top references are mostly

    http://manatee.mojam.com/python-glossary

    which seems not to have caught on so far (mea culpa too, since it takes volunteers ;-/ ).

    Anyway, my take on 'namespace' is a name->value mapping. I.e., pretty abstract.
    Then follows a discussion of various python mechanisms that do that (whether via
    a single dict's d[name] mapping or the infinite d.get(name, default) mapping,
    or the mapping implicit in the search, e.g., for a bare name using a function's
    local name lookup rules (local, closure, global, builtin) -- not to mention the
    mapping names undergo when used as attribute names in various ways.

    Compared to other languages, python's name spaces (in my sense) seem to have
    evolved interestingly ;-) I am wondering whether the future holds a more unified
    model of namespaces and their access mechanisms, so most inspect and sys._getframe
    name access hacks will be obviated.

    Re defintions, perhaps it is time to reinvigorate Skip's wiki or something like that?

    There was an interesting thread re improving python doc functionality at

    http://mail.python.org/pipermail/python-list/2004-May/219682.html

    An online extension of help() maybe taking a syntax clue from google ,like

    help('define:xxx')

    might be an interesting hook into a glossary of definitions.

    Regards,
    Bengt Richter
     
    Bengt Richter, Sep 4, 2004
    #9
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