>>>>> "GvR" == Guido van Rossum <guido@python.org> writes:
>> If we get lexical scoping, there should be a fast (built-in)
>> way to get at all the accessible names from Python.
>> I.e. currently I can do d = globals().copy() d.update(locals())
>> and know that `d' contains a dictionary of available names,
>> with the right overloading semantics. (PEP 42 now includes a
>> feature request to make vars() do this by default.)
GvR> Note that I just deleted that feature request from PEP 42 --
GvR> vars() or locals() returns the dictionary containing the
GvR> variables, and you can't just change the semantics to return
GvR> a newly copied dictionary (which could be quite expensive
GvR> too!).
Saw that. I was just thinking that locals() already does what
vars()-no-args does, so why have two ways to do the same thing?
GvR> I don't think you need to have a mechanism to find all
GvR> accessible names; I don't see a common use for that. It's
GvR> sufficient to have a mechanism to look up any specific name
GvR> according to whatever mechanism we decide upon. This is
GvR> needed for internal use of course; it can also be useful for
GvR> e.g. variable substitution mechanisms like the one you
GvR> recently proposed or Ping's Itmpl.
Ah, something like this then:
-------------------- snip snip --------------------
import sys
from UserDict import UserDict
class NamesDict(UserDict):
def __init__(self, frame):
self.__frame = frame
UserDict.__init__(self)
def __getitem__(self, key):
if self.data.has_key(key):
return self.data[key]
locals = self.__frame.f_locals
if locals.has_key(key):
return locals[key]
globals = self.__frame.f_globals
if globals.has_key(key):
return globals[key]
raise KeyError, key
def _(s):
try: raise 'oops'
except: frame = sys.exc_info()[2].tb_frame.f_back
return s % NamesDict(frame)
theirs = 'theirs'
def give(mine, yours):
print _('mine=%(mine)s, yours=%(yours)s, theirs=%(theirs)s')
-------------------- snip snip --------------------
Python 2.0 (#128, Oct 18 2000, 04:48:44)
[GCC egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)] on linux2
Type "copyright", "credits" or "license" for more information.
>>> import dict
>>> dict.give('mine', 'yours')
mine=mine, yours=yours, theirs=theirs
>>>
-Barry
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