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Multi-line string with extra space (preserved indentation)
...o use a helper function and some variable substitution tricks:
unset text
_() { text="${text}${text+
}${*}"; }
# That's an empty line which demonstrates the reasoning behind
# the usage of "+" instead of ":+" in the variable substitution
# above.
_ ""
_ "this is line one"
_ "this is line two"
_ "...
Python extending with - using super() Python 3 vs Python 2
...
super() (without arguments) was introduced in Python 3 (along with __class__):
super() -> same as super(__class__, self)
so that would be the Python 2 equivalent for new-style classes:
super(CurrentClass, self)
for old-style classes you can always use:
class Classname(OldStyleParen...
How do I correctly clean up a Python object?
__del__(self) above fails with an AttributeError exception. I understand Python doesn't guarantee the existence of "global variables" (member data in this context?) when __del__() is invoked. If that is the case and this is the reason for the exception, how do I make sure the object destructs...
What would a “frozen dict” be?
...ict(collections.Mapping):
"""Don't forget the docstrings!!"""
def __init__(self, *args, **kwargs):
self._d = dict(*args, **kwargs)
self._hash = None
def __iter__(self):
return iter(self._d)
def __len__(self):
return len(self._d)
def __getitem__...
理解Python的 with 语句 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...hat the statement after with has to evaluate an object that responds to an __enter__() as well as an __exit__() function.
这看起来充满魔法，但不仅仅是魔法，Python对with的处理还很聪明。基本思想是with所求值的对象必须有一个__enter__()方法，一个__exit__()...
How do I check OS with a preprocessor directive?
...ecks. Here are a few of them, with links to where they're found:
Windows
_WIN32 Both 32 bit and 64 bit
_WIN64 64 bit only
Unix (Linux, *BSD, Mac OS X)
See this related question on some of the pitfalls of using this check.
unix
__unix
__unix__
Mac OS X
__APPLE__
__MACH__
Both are de...
MySQL vs MongoDB 1000 reads
...nk of time.
foreach ($cursor as $obj)
{
//echo $obj["thread_title"] . "<br><Br>";
}
while the other chunk is spend yacking up a bunch of rand numbers.
function get_15_random_numbers()
{
$numbers = array();
for($i=1;$i<=15;$i++)
{
$numbers[] =...
what does the __file__ variable mean/do?
...
When a module is loaded from a file in Python, __file__ is set to its path. You can then use that with other functions to find the directory that the file is located in.
Taking your examples one at a time:
A = os.path.join(os.path.dirname(__file__), '..')
# A is the par...
Print all properties of a Python Class [duplicate]
...
vars only works if you are using __dict__ to store the attributes (which is the default behaviour for Python objects). Refer to @BasicWolf's answer if you are using __slots__
– Cyctemic
Feb 20 '14 at 10:23
...
Can modules have properties the same way that objects can?
...ance. So, for example, your m.py module file could be:
import sys
class _M(object):
def __init__(self):
self.c = 0
def afunction(self):
self.c += 1
return self.c
y = property(afunction)
sys.modules[__name__] = _M()
...