How to pass parameter to a module?

[M-a-S]

I'd like to parametrize a module. That is, to set and pass
some values into the module, while it is being imported.
I tried this:

# sub_1.py -- main program
extern = "OK"
import sub_2
print sub_2.noway # prints 'no extern' :-(
# EOF

# sub_2.py -- parametrized module, parameter is the 'extern' var
try:
noway = extern
except:
noway = 'no extern'
# EOF

You can guess, it doesn't work.
How can I pass the parameter? Can I?
M-a-S

 

[Daniel Dittmar]

I'd like to parametrize a module. That is, to set and pass
some values into the module, while it is being imported.
I tried this:

# sub_1.py -- main program
extern = "OK"
import sub_2
print sub_2.noway # prints 'no extern' :-(
# EOF

# sub_2.py -- parametrized module, parameter is the 'extern' var
try:
noway = extern
except:
noway = 'no extern'
# EOF

You can guess, it doesn't work.
How can I pass the parameter? Can I?

Create an additional module sub_2_parameters:
# sub_1.py -- main program
import sub_2_parameters
sub_2_parameters.extern = "OK"
import sub_2

# sub_2.py -- parametrized module, parameter is the 'extern' var
import sub_2_parameters
try:
noway = sub_2_parameters.extern
except:
noway = 'no extern'
# EOF

Note that modules are imported only once so you cannot import sub_2 with one
set of parameters into one module and with another set of variables into
another.

Depending on your problem, it might be better to use the builtin execfile,
because you can pass a dictionary with the parameters to the call.

Daniel

 

[Ulrich Petri]

I'd like to parametrize a module. That is, to set and pass
some values into the module, while it is being imported.
I tried this:

# sub_1.py -- main program
extern = "OK"
import sub_2
print sub_2.noway # prints 'no extern' :-(
# EOF

# sub_2.py -- parametrized module, parameter is the 'extern' var
try:
noway = extern
except:
noway = 'no extern'
# EOF

It looks like you are using modules where you would rather use functions.
exp:
-------------------cut---------
def sub2(blah=None):
if blah is None:
return "no extern"
else:
return blah

sub2('test')
sub2()

HTH

Ciao Ulrich

 

[M-a-S]

I thought about the third module. It doesn't sound good.
I hoped there're some tricks with __dict__, frames and
other __...__ objects.

For now, this is what does the task:

# sub_2.py
''' The documentation will look like this:
To set the size of dictionary and search depth,
do before including (default values are shown):
import string
string.sub_2_dictionary_size = 10 # in megabytes
string.sub_2_search_depth = 1000 # in nodes
string.sub_2_max_responce_time = 100 # seconds
'''
import string # it's used in sub_2 anyway
# parameters
try: _DICT_SZ = string.sub_2_dictionary_size
except: _DICT_SZ = 10
try: _DEPTH = string.sub_2_search_depth
except: _DEPTH = 1000
try: _RTIME = string.sub_2_max_responce_time
except: _RTIME = 100
# now the stuff
def do_the_job():
return "Processing with dict=%d depth=%d rtime=%d" % (_DICT_SZ,_DEPTH,_RTIME)
# EOF

# sub_1.py
import string # actually, some module, which is used in sub_2
string.sub_2_dictionary_size = 20 # megabytes
string.sub_2_search_depth = 5000 # nodes
# let's leave sub_2_max_responce_time default
import sub_2
print sub_2.do_the_job()
# EOF

M-a-S

 

[Michael Peuser]

I thought about the third module. It doesn't sound good.
I hoped there're some tricks with __dict__, frames and
other __...__ objects.

Well, there are some tricks ;-)


myVariable='great surprise'
import x
........

"This is modul X"
import sys
print sys.modules['__main__'].myVariable


But generally the namespace of a module is ... the module.

Kindly
Michael P

 

[M-a-S]

That's what I asked. Thanks!
M-a-S

I thought about the third module. It doesn't sound good.
I hoped there're some tricks with __dict__, frames and
other __...__ objects.

Well, there are some tricks ;-)


myVariable='great surprise'
import x
.......

"This is modul X"
import sys
print sys.modules['__main__'].myVariable


But generally the namespace of a module is ... the module.

Kindly
Michael P

 

[Hung Jung Lu]

I'd like to parametrize a module. That is, to set and pass
some values into the module, while it is being imported.

There are many ways.

(However, classes may fit your need better. "Passing parameters to a
module" is not a common practice, as far as I know.)

(1) Use a built-in namespace variable.

import __builtin__
__builtin__.myvar = 3
print myvar

This is a hack. I have been screamed at for mentioning it.

(2) Hack your favorite (non-builtin) module. The module could be any
of the standard library modules, or your own third module.

import sys
sys.myvar = 3

(3) Use environmental variables.

import os
os.environ['myvar'] = 'hello'

You get the idea. Python has three namespaces: built-in, global, and
local. Since global and local namespaces won't go over to the other
module, you need to rely on the built-in namespace, one way or
another. How you want to structure your data (by using the built-in
namespace, a module, a class, a dictionary or any other entities that
can hold a name entry), it's entirely up to you.

Hung Jung

 

[M-a-S]

Thank you!

I'd like to parametrize a module. That is, to set and pass
some values into the module, while it is being imported.

There are many ways.

(However, classes may fit your need better. "Passing parameters to a
module" is not a common practice, as far as I know.)

(1) Use a built-in namespace variable.

import __builtin__
__builtin__.myvar = 3
print myvar

This is a hack. I have been screamed at for mentioning it.

(2) Hack your favorite (non-builtin) module. The module could be any
of the standard library modules, or your own third module.

import sys
sys.myvar = 3

(3) Use environmental variables.

import os
os.environ['myvar'] = 'hello'

You get the idea. Python has three namespaces: built-in, global, and
local. Since global and local namespaces won't go over to the other
module, you need to rely on the built-in namespace, one way or
another. How you want to structure your data (by using the built-in
namespace, a module, a class, a dictionary or any other entities that
can hold a name entry), it's entirely up to you.

Hung Jung