About a month ago, there was a thread on auto-assigning decorators for
__init__. One by André Roberge is here:
http://groups.google.com/group/comp.lang.python/browse_frm/
thread/32b421bbe6caaeed/0bcd17b1fa4fb07c?#0bcd17b1fa4fb07c
This works well for simple cases, but doesn't take keyword arguments or
set default values. I wrote a more extensive version implementing python
call semantics, but it seemed awkard to be repeating something the
compiler does already, so I tried execing a function definition on the
fly with the right parameters that would function as the decorator. Like
this (adjust the indentation variable if it throws a syntax error)
def autoassign(_init_):
import inspect
import functools
argnames, _, _, defaults = inspect.getargspec(_init_)
argnames = argnames[1:]
indentation = ' '
settings = ['self.%s = %s' % (arg[1:], arg) for arg in argnames
if arg[0] == '_']
if len(settings) <= 0:
return _init_
if defaults is None:
args = argnames[:]
else:
args = argnames[:-len(defaults)]
for key, value in zip(argnames[-len(defaults):],defaults):
args.append('%s=%s' % (key, repr(value)))
template = """def _autoassign(self, %(args)s):
%(setting)s
_init_(self, %(argnames)s)
""" % {'args' : ", ".join(args), 'setting' : "\n".join(['%s%s' %
(indentation, setting) for setting
in settings]), 'argnames' : ', '.join(argnames)}
try:
exec template
except SyntaxError, e:
raise SyntaxError('%s. line: %s. offset %s:\n%s' %
(e.msg, e.lineno, e.offset, template))
return _autoassign
Which creates what looked like the right template, but when instantiating
a class that uses that (eg
class A(object):
@autoassign
def __init__(self,_a):
pass
a = A(3)
it throws a
NameError: global name '_init_' is not defined
Is there a way to bind the _init_ name at exec time?
Thanks,
ale
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