Type of __builtins__ changes from module import to execution?

[Adam Hupp]

I've noticed some unexpected behavior with __builtins__ during module
import. It seems that during module import __builtins__ is a dict
but at all other times it is a module.

For example, if the file testmod.py has these contents:

print type(__builtins__)
print "has str attr", hasattr(__builtins__, 'str')

The output differs depending on how it is run:

$ python ~/testmod.py
<type 'module'>
has str True

vs.

$ python -c 'import testmod'
<type 'dict'>
has str False

Anyone know if there a reason for this behavior? Is it a bug? I've
seen this in 2.4 and 3.0.

-Adam

 

[Marc Christiansen]

I've noticed some unexpected behavior with __builtins__ during module
import. It seems that during module import __builtins__ is a dict
but at all other times it is a module.

For example, if the file testmod.py has these contents:

print type(__builtins__)
print "has str attr", hasattr(__builtins__, 'str')

The output differs depending on how it is run:

$ python ~/testmod.py
<type 'module'>
has str True

vs.

$ python -c 'import testmod'
<type 'dict'>
has str False

Anyone know if there a reason for this behavior? Is it a bug? I've
seen this in 2.4 and 3.0.

-Adam

No, it's not a bug. __builtins__ is an implementation detail. You want
__builtin__. See <http://docs.python.org/lib/module-builtin.html>

Ciao
Marc