unbinding a global variable in Python

[Mark Tarver]

In Lisp this is done so

(setq *g* 0) 0

0

(makunbound '*g*) *g*

*g*

error: unbound variable

How is this done in Python?

Mark

 

[Diez B. Roggisch]

In Lisp this is done so

error: unbound variable

How is this done in Python?

Mark

Traceback (most recent call last):

Be aware of functions that declare global variables though:

.... global bar
.... bar = 10
....Traceback (most recent call last):
10


Diez

 

[Mark Tarver]

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'foo' is not defined



Be aware of functions that declare global variables though:


...     global bar
...     bar = 10
...>>> foo()

Traceback (most recent call last):


10

Diez- Hide quoted text -

- Show quoted text -

Great; and how can I test to see if a global is bound?

e.g Lisp

(setq *g* 0) 0

(boundp '*g*)

t

Mark

 

[Hrvoje Niksic]

t

'foo' in globals()

 

[Peter Otten]

In Lisp this is done so

error: unbound variable

How is this done in Python?

Often it is a better choice to initialize the global with a sentinel:

g = None

# ...
g = "something meaningful"

# the equivalent of checking whether it's bound:
if g is not None:
# use g

# the eqivalent of unbinding:
g = None

Peter