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Multiple levels of 'collection.defaultdict' in Python
... @ScienceFriction Anything specific that you need help with? When d[new_key] is accessed, it will call the lambda which will create a new defaultdict(int). And when d[existing_key][new_key2] is accessed, a new int will be created.
– interjay
Oct 11 '13 at 1...
Python != operation vs “is not”
...ght hand side and the left hand side are equal objects (according to their __eq__ or __cmp__ methods.)
is is an identity test. It checks whether the right hand side and the left hand side are the very same object. No methodcalls are done, objects can't influence the is operation.
You use is (and i...
How can I create a copy of an object in Python?
... get a copy method (in 2, you'd use a slice to make a copy):
>>> a_list = list('abc')
>>> a_copy_of_a_list = a_list.copy()
>>> a_copy_of_a_list is a_list
False
>>> a_copy_of_a_list == a_list
True
Shallow Copies
Shallow copies are just copies of the outermost cont...
Creating C macro with ## and __LINE__ (token concatenation with positioning macro)
...PASTE2(x, y) TOKENPASTE(x, y)
#define UNIQUE static void TOKENPASTE2(Unique_, __LINE__)(void) {}
Then, __LINE__ gets expanded to the line number during the expansion of UNIQUE (since it's not involved with either # or ##), and then the token pasting happens during the expansion of TOKENPASTE.
It ...
Why is Python 3.x's super() magic?
...lf):
return super(Foo, self).baz() + 42
Spam = Foo
Foo = something_else()
Spam().baz() # liable to blow up
The same applies to using class decorators where the decorator returns a new object, which rebinds the class name:
@class_decorator_returning_new_class
class Foo(Bar):
def baz...
'is' versus try cast with null check
...ing)
{
var x = (string) o;
}
This translates to the following IL:
IL_0000: nop
IL_0001: ldstr "test"
IL_0006: stloc.0 // o
IL_0007: ldloc.0 // o
IL_0008: isinst System.String
IL_000D: ldnull
IL_000E: cgt.un
IL_0010: stloc.1
IL_0011: ldloc....
Performance difference for control structures 'for' and 'foreach' in C#
...ed
{
// Code size 49 (0x31)
.maxstack 1
.locals init (object V_0,
valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<object> V_1)
IL_0000: ldarg.0
IL_0001: callvirt instance valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<!0>...
What does multicore assembly language look like?
...els in the wild that boot from USB drives or "floppy" disks - here's an x86_32 version written in assembler using the old TSS descriptors that can actually run multi-threaded C code (github.com/duanev/oz-x86-32-asm-003) but there is no standard library support. Quite a bit more than you asked for b...
What is the difference between class and instance attributes?
...> a.foo.append(5)
>>> b.foo
[5]
>>> class A:
... def __init__(self): self.foo = []
>>> a, b = A(), A()
>>> a.foo.append(5)
>>> b.foo
[]
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How do I get logs/details of ansible-playbook module executions?
...dd the following lines to your ansible configuration file:
[defaults]
log_path=/path/to/logfile
Ansible will look in several places for the config file:
ansible.cfg in the current directory where you ran ansible-playbook
~/.ansible.cfg
/etc/ansible/ansible.cfg
...