Matteo wrote:
> I am trying to get Python to extract attributes in full dotted form
> from compiled expression. For instance, if I have the following:
>
> param = compile('a.x + a.y','','single')
>
> then I would like to retrieve the list consisting of ['a.x','a.y'].
> I have tried using inspect to look at 'co_names', but when I do that,
You can have a look at the compiler package. A very limited example:
import compiler
import compiler.ast
import sys
class Visitor:
def __init__(self):
self.names = []
def visitName(self, node):
self.names.append(node.name)
def visitGetattr(self, node):
dotted = []
n = node
while isinstance(n, compiler.ast.Getattr):
dotted.append(n.attrname)
n = n.expr
try:
dotted.append(n.name)
except AttributeError:
print >> sys.stderr, "ignoring", node
else:
self.names.append(".".join(reversed(dotted)))
if __name__ == "__main__":
expr = " ".join(sys.argv[1:])
visitor = Visitor()
compiler.walk(compiler.parse(expr), visitor)
print "\n".join(visitor.names)
Output:
$ python dotted_names.py "a + b * (c + sin(d.e) + x.y.z)"
a
b
c
sin
d.e
x.y.z
$ python dotted_names.py "a + b * ((c + d).e + x.y.z)"
ignoring Getattr(Add((Name('c'), Name('d'))), 'e')
a
b
x.y.z
Peter
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