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Python memoising/deferred lookup property decorator
...
from boltons.cacheutils import cachedproperty
class Foo(object):
def __init__(self):
self.value = 4
@cachedproperty
def cached_prop(self):
self.value += 1
return self.value
f = Foo()
print(f.value) # initial value
print(f.cached_prop) # cached property is c...
Get the name of the currently executing method
...
Even better than my first answer you can use __method__:
class Foo
def test_method
__method__
end
end
This returns a symbol – for example, :test_method. To return the method name as a string, call __method__.to_s instead.
Note: This requires Ruby 1.8.7.
...
Clang vs GCC for my Linux Development project
...inux-gnu/4.3.4/include/g++-v4/ostream:112: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits...
namedtuple and default values for optional keyword arguments
...Node()
Node(val=None, left=None, right=None)
Before Python 3.7
Set Node.__new__.__defaults__ to the default values.
>>> from collections import namedtuple
>>> Node = namedtuple('Node', 'val left right')
>>> Node.__new__.__defaults__ = (None,) * len(Node._fields)
>&g...
How to get a function name as a string?
...
my_function.__name__
Using __name__ is the preferred method as it applies uniformly. Unlike func_name, it works on built-in functions as well:
>>> import time
>>> time.time.func_name
Traceback (most recent ...
Using logging in multiple modules
...ave a logger defined like this:
import logging
logger = logging.getLogger(__name__)
near the top of the module, and then in other code in the module do e.g.
logger.debug('My message with %s', 'variable data')
If you need to subdivide logging activity inside a module, use e.g.
loggerA = loggin...
OS X10.9 环境下部署 QT5.3.1 常见的编译问题 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...件中加入对应的SDK版本:
1
QMAKE_MAC_SDK = macosx10.9
3、:-1: error: [ui_mainwindow.h] Trace/BPT trap: 5
dyld: Library not loaded: /work/build/______________________________PADDING______________________________/lib/QtCore.framework/Versio...
Python's equivalent of && (logical-and) in an if-statement
...actually
evaluated because of the print statements:
>>> def print_and_return(value):
... print(value)
... return value
>>> res = print_and_return(False) and print_and_return(True)
False
As you can see only one print statement is executed, so Python really didn't even lo...
Is it possible to make abstract classes in Python?
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# Python 2
from abc import ABCMeta, abstractmethod
class Abstract:
__metaclass__ = ABCMeta
@abstractmethod
def foo(self):
pass
Whichever way you use, you won't be able to instantiate an abstract class that has abstract methods, but will be able to instantiate a subclass th...
Python: How do I make a subclass from a superclass?
...
# Initialize using Parent
#
class MySubClass(MySuperClass):
def __init__(self):
MySuperClass.__init__(self)
Or, even better, the use of Python's built-in function, super() (see the Python 2/Python 3 documentation for it) may be a slightly better method of calling the parent for ...