从python中的模块导入运算符的语法

Question

I'm working with this library , which (very reasonably because it is translating from another language's idioms) makes heavy use of operator redefinition.

Usage begins with from parsec import * which in general, I try to avoid, and rather keep my namespace. Something more like import parsec as p then using the sub functions and every operator, explicitly.

This works for some functions, like p.many1() or p.spaces() or p.regex() .

However, this also leaves me trying to import name-spaced operators, and that looks even less pythonic.

For example, the bitwise >> and << are redefined. Here is a real-world usage .

Not only does trying to use a namespace to call these operators also look unpythonic, it's not even clear to me how to do it: p.>> ? As you can see, this is a syntax error:

>>> import parsec as p
>>> p.>> p.many()
  File "<stdin>", line 1
    p.>>
       ^
SyntaxError: invalid syntax

This leaves me deciding I want to import the operators implicitly, that is, to call >> without a namespace, but to import the non-operators inside a p namespace.

edit update

To be clear, my question is:

How can I import the functions like many1() with a namespace as p.many1(), and import the operator functions like "+" ">>" "<<" nakedly, without a namespace?

end update

While I can do

import parsec as p

To get the non-operator functions, it's not clear to me how to say:

from parsec import >>

As the following attempts at explicitly importing operators all fail:

>>> from parsec import >>
  File "<stdin>", line 1
    from parsec import >>
                        ^
SyntaxError: invalid syntax
>>> from parsec import (>>)
  File "<stdin>", line 1
    from parsec import (>>)
                         ^
SyntaxError: invalid syntax
>>> from parsec import ">>"
  File "<stdin>", line 1
    from parsec import ">>"
                          ^
SyntaxError: invalid syntax
>>> from parsec import __lshift__, __rshift__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name '__lshift__' from 'parsec' ()

How can I import these?

Answer 1

I think the operators are defined as methods on the parser objects, so you don't import them as operators explicitly. If you import the other objects with ap namespace, and you perform the operator operations on them, it will "just work" because the Parser class has these defined.