dynamically adding some of one module's functions to another

[Gabriel Rossetti]

Hello everyone,

I'm trying to import some modules into another's namespace (network_utils)

network_utils.py:

import utils
import constants as main_const
from services import constants as srv_const
from plugins import constants as plg_const

#
# Import all the message creation functions
#
f = dict([ (f, eval("utils." + f)) for f in dir(utils) if
f.startswith("create") ])
__builtins__.update(f)
del utils

#
# Create a virgin namespace
#
class constants:
"""
An aggragation of L{constants},
L{services.constants}, &
L{plugins.constants}
"""
pass

#
# Import all the constants into the new namespace
#
f = dict([ (f, eval("main_const." + f)) for f in dir(main_const) if
f.isupper() ])
constants.__dict__.update(f)
del main_const
f = dict([ (f, eval("srv_const." + f)) for f in dir(srv_const) if
f.isupper() ])
constants.__dict__.update(f)
del srv_const
f = dict([ (f, eval("plg_const." + f)) for f in dir(plg_const) if
f.isupper() ])
constants.__dict__.update(f)
del plg_const


now, if I import network_utils somewhere, and try to call
network_utils.myFunction() I get :
Traceback (most recent call last):
File "<console>", line 1, in <module>
AttributeError: 'module' object has no attribute 'myFunction'

but if I try to access the constants class:
'none'

it works, how come?

Thank you,
Gabriel

 

[Bruno Desthuilliers]

Gabriel Rossetti a écrit :

Hello everyone,

I'm trying to import some modules into another's namespace (network_utils)

network_utils.py:

import utils
import constants as main_const
from services import constants as srv_const
from plugins import constants as plg_const

#
# Import all the message creation functions
#
f = dict([ (f, eval("utils." + f)) for f in dir(utils) if
f.startswith("create") ])

As usual, you don't need eval here. Use getattr instead:

create_functions = dict(
(name, getattr(utils, name)
for name in dir(utils)
if name.startswith('create')
)

__builtins__.update(f)

Python 2.5.1 (r251:54863, Apr 6 2008, 17:20:35)
[GCC 4.1.2 (Gentoo 4.1.2 p1.0.2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.Traceback (most recent call last):

Anyway, adding to builtins is certainly not the best thing to do. I
don't know what you're trying to do here, but looks like a very ugly
mess to me.

del utils

#
# Create a virgin namespace
#
class constants:
"""
An aggragation of L{constants},
L{services.constants}, &
L{plugins.constants}
"""
pass

#
# Import all the constants into the new namespace
#
f = dict([ (f, eval("main_const." + f)) for f in dir(main_const) if
f.isupper() ])
constants.__dict__.update(f)
del main_const
f = dict([ (f, eval("srv_const." + f)) for f in dir(srv_const) if
f.isupper() ])
constants.__dict__.update(f)
del srv_const
f = dict([ (f, eval("plg_const." + f)) for f in dir(plg_const) if
f.isupper() ])
constants.__dict__.update(f)
del plg_const

Yuck.

In your constants.py file, just add the relevant imports:

from services.constants import *
from plugins.constants import *

And then in your network_utils file:

import constants

But this is still a mess to me. The nice point with explicit import and
modules namespaces is that you at least have a chance to know where a
given symbol comes from.

now, if I import network_utils somewhere, and try to call
network_utils.myFunction() I get :

Traceback (most recent call last):
File "<console>", line 1, in <module>
AttributeError: 'module' object has no attribute 'myFunction'

And ? Where is the name myFunction bound in the above code ?

but if I try to access the constants class:

'none'

it works, how come?

I suppose NO_DATA_TYPE is defined somewhere in one of your constants.py
files.

Instead of messing with eval and builtins and wonder why something
"works" and why something else doesn't, I strongly suggest you (re)read
the part about imports, packages, modules etc in the FineManual.