six: burn the bridges

Let’s try and automatically un-six python source. Here’s a quick audit of what six does and how to undo it in python 3:

From the docs:

trivial replacements

• six.text_type => str
• six.binary_type => bytes
• six.class_types => (type,)
• six.string_types => (str,)
• six.integer_types => (int,)
• six.unichr => chr
• six.iterbytes => iter
• six.print_(...) => print(...)
• six.exec_(c, g, l) => exec(c, g, l)
• six.advance_iterator(it) => next(it)
• six.next(it) => next(it)
• six.callable(x) => callable(x)

trivial removals:

• python_2_unicode_compatible (remove decorator)

  @six.python_2_unicode_compatible
  class C: pass
  

requires parsing a function call

• six.u('foo') => 'foo'
• six.byte2int(bs) => bs[0]
• six.indexbytes(bs, i) => bs[i]
• six.iteritems(dct) => dct.items() # also {iter,view}{items,keys,values}
• six.create_unbound_method(fn, cls) => fn
• six.get_unbound_method(meth) => meth
• six.get_method_function(meth) => meth.__func__
• six.get_method_self(meth) => meth.__self__
• six.get_function_closure(fn) => fn.__closure__
• six.get_function_code(fn) => fn.__code__
• six.get_function_defaults(fn) => fn.__defaults__
• six.get_function_globals(fn) => fn.__globals__
• six.assertCountEqual(self, arg1, arg2) => self.assertCountEqual(arg1, arg2)
• six.assertRaisesRegex(self, fn, *a, **k) => self.assertRaisesRegex(fn, *a, **k)
• six.assertRegex(self, *a) => self.assertRegex(*a)

maybe replace with literal?

• six.b => replace with bytes literal?

need to know that you’re not in a place where a raise statement is invalid

• six.raise_from(exc, exc_from) => raise exc from exc_from
• six.reraise(tp, exc, tb) => raise exc.with_traceback(tb)

probably can reuse the “new style class” logic

• class C(six.Iterator): => class C:

requires multiple function call parses, probably hard

• class C(six.with_metaclass(Meta, Base)): => class C(Base, metaclass=Meta):

• (rewriting add_metaclass)

  @six.add_metaclass(mcs)
  class C(...): pass
  

  to

  class C(..., metaclass=mcs): pass
  

probably can’t do (requires introducing an import)

• six.wraps(fn) => functools.wraps(fn): https://github.com/asottile/reorder_python_imports/pull/59

Note that for six.moves I’m planning on handling that in reorder-python-imports

[asottile]

with #149 I think I’m finally calling this done!

I’m planning to try and do something clever with version-guarded blocks later

[hugovk]

Good work!