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How do I get the number of elements in a list?
...objects with a "size" in Python, in particular, have an attribute called ob_size, where the number of elements in the object is cached. So checking the number of objects in a list is very fast.
But if you're checking if list size is zero or not, don't use len - instead, put the list in a boolean co...
How do I determine the size of an object in Python?
...rieve the size and would cause a
TypeError.
getsizeof calls the object’s
__sizeof__ method and adds an additional garbage collector overhead
if the object is managed by the
garbage collector.
See recursive sizeof recipe for an example of using getsizeof() recursively to find the size of containers...
How to access outer class from an inner class?
...f):
return Outer.Inner(self)
class Inner(object):
def __init__(self, outer_instance):
self.outer_instance = outer_instance
self.outer_instance.somemethod()
def inner_method(self):
self.outer_instance.anothermethod()
...
How to read a single character from the user?
...Windows, Linux and OSX: http://code.activestate.com/recipes/134892/
class _Getch:
"""Gets a single character from standard input. Does not echo to the
screen."""
def __init__(self):
try:
self.impl = _GetchWindows()
except ImportError:
self.impl = _Ge...
Why aren't python nested functions called closures?
...variable from an enclosing scope that has finished its execution.
def make_printer(msg):
def printer():
print msg
return printer
printer = make_printer('Foo!')
printer()
When make_printer is called, a new frame is put on the stack with the compiled code for the printer function a...
Are nested try/except blocks in python a good programming practice?
...EAFP.
Personally, I prefer to avoid nesting when it's not necessary:
def __getattribute__(self, item):
try:
return object.__getattribute__(item)
except AttributeError:
pass # fallback to dict
try:
return self.dict[item]
except KeyError:
raise Attrib...
Undefined reference to `pow' and `floor'
...
You can also use LD_PRELOAD to tell ld runtime linker to include libm.so in the memory map and symbol table of the process, so these symbols get loaded and everything works as expected
– debuti
May 28 '18 ...
【解决】scrapyd启动job时报错：exceptions.TypeError: __init__() got an ...
【解决】scrapyd启动job时报错：exceptions.TypeError: __init__() got an unexpected keyword argument '_job'进入项目spiders目录, 修改 spider py 文件（你自己的spider的主文件）：def __init__(self):改为：def __init__(self, *args, **kwargs):最后不要忘了重新部署一...
How can I find script's directory with Python? [duplicate]
...
You need to call os.path.realpath on __file__, so that when __file__ is a filename without the path you still get the dir path:
import os
print(os.path.dirname(os.path.realpath(__file__)))
...
编译器内部的秘密--微软的编译器是如何解析Try/Catch/Throw的 - C/C++ - 清...
...这并不是应该由编译器该干的活。这行语句会变成对函数_CxxThrowException (函数来自MSVCR100.dll或其他类似版本的dll)的调用。 这个函数有编译器内部构建。你喜欢的话，你可以自己调用它。这个函数的第一个参数是指向抛出的异常...