Hello,
is it at all possible to set new vars (or any symbol) into an existing scope
(typically locals())?
scope[name] = value
raises by me an error like:
TypeError: 'mappingproxy' object does not support item assignment
I guess 'mappingproxy' is the implementation name of a scope (here, local), and
I thought scopes were just dicts; so what is the issue? Do you see an alternative?
Context: This is used in a tool func that names defined objects of a given
(matching patterns) in a given scope (which forms a grammar/parser). The base
issue is that objects don't know their names, which in my case (and many more)
are useful, in fact necessary, for programmer feedback, testing, debugging and
more. However, at times a developper needs variants of a given pattern (matching
same format, eg name=symbol), but they should be distinct objects: meaning copy,
meaning setting the new variant into the scope.
The tool func (a static method of Pattern, in fact), is just:
def name (scope):
''' Name all defined patterns of a given grammar's scope.
[... more doc ...]
'''
for name, pat in scope.items():
if isinstance(pat, Pattern):
# Just name pat:
pat.name = name
# ... plus detail ...
But the body should be:
for name, pat in scope.items():
if isinstance(pat, Pattern):
# Possibly make copy in case pat is already named:
if pat.name:
new_pat = copy(pat)
new_pat.name = name
scope[name] = new_pat # error ***
# Else, just name pat:
else:
pat.name = name
# ... plus detail ...
I'm blocked. Users can do it by hand, but it's pretty annoying and a sure source
of bugs (there is more than just naming: if users define a variant, they
probably want to define a different match action: if no copy, then the action is
set on the original pattern...). This should be automagic.
Denis
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