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What are the differences between NP, NP-Complete and NP-Hard?
...njunction (ANDs) of 3-clause disjunctions (ORs), statements of the form
(x_v11 OR x_v21 OR x_v31) AND
(x_v12 OR x_v22 OR x_v32) AND
... AND
(x_v1n OR x_v2n OR x_v3n)
where each x_vij is a boolean variable or the negation of a variable from a finite predefined list (x_1, x...
STL中map容器使用自定义key类型报错详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
...定义一个结构体来试试:[cpp]view plaincopystructa{char*pName;intm_a;} 引言
STL的map容器中,key的类型是不是随意的呢?
实践
编写测试代码
定义一个结构体来试试:
struct a
{
char* pName;
int m_a;
};
...
map<a, int> mp;
a ...
Checking if an instance's class implements an interface?
...
As therefromhere points out, you can use class_implements(). Just as with Reflection, this allows you to specify the class name as a string and doesn't require an instance of the class:
interface IInterface
{
}
class TheClass implements IInterface
{
}
$interfaces = cl...
How to make a class property? [duplicate]
...re's how I would do this:
class ClassPropertyDescriptor(object):
def __init__(self, fget, fset=None):
self.fget = fget
self.fset = fset
def __get__(self, obj, klass=None):
if klass is None:
klass = type(obj)
return self.fget.__get__(obj, klass)(...
List all base classes in a hierarchy of given class?
...gt;
>>> import inspect
>>> inspect.getmro(B)
(<class '__main__.B'>, <class '__main__.A'>, <type 'object'>)
share
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Can a decorator of an instance method access the class?
...decorator, perhaps something like this (warning: untested code).
def class_decorator(cls):
for name, method in cls.__dict__.iteritems():
if hasattr(method, "use_class"):
# do something with the method and class
print name, cls
return cls
def method_decorator(v...
difference between variables inside and outside of __init__()
...
Variable set outside __init__ belong to the class. They're shared by all instances.
Variables created inside __init__ (and all other method functions) and prefaced with self. belong to the object instance.
...
What does “mro()” do?
...
Follow along...:
>>> class A(object): pass
...
>>> A.__mro__
(<class '__main__.A'>, <type 'object'>)
>>> class B(A): pass
...
>>> B.__mro__
(<class '__main__.B'>, <class '__main__.A'>, <type 'object'>)
>>> class C(A): pa...
How to print to console in pytest?
...as printed to standard out in that particular test.
For example,
def test_good():
for i in range(1000):
print(i)
def test_bad():
print('this should fail!')
assert False
Results in the following output:
>>> py.test tmp.py
============================= test session s...
What is __init__.py for?
What is __init__.py for in a Python source directory?
12 Answers
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