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correct way to define class variables in Python [duplicate]
...hey are just two different kinds of class elements:
Elements outside the __init__ method are static elements; they belong to the class.
Elements inside the __init__ method are elements of the object (self); they don't belong to the class.
You'll see it more clearly with some code:
class MyClass...
Why do we use __init__ in Python classes?
...ical piece of understanding: the difference between a class and an object. __init__ doesn't initialize a class, it initializes an instance of a class or an object. Each dog has colour, but dogs as a class don't. Each dog has four or fewer feet, but the class of dogs doesn't. The class is a concept o...
Relative paths in Python
..., you want to do something like this:
import os
dirname = os.path.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
This will give you the absolute path to the file you're looking for. Note that if you're using setuptools, you should probably use its package re...
Hashing a dictionary?
...d make a frozenset with the dict's items and use hash():
hash(frozenset(my_dict.items()))
This is much less computationally intensive than generating the JSON string or representation of the dictionary.
UPDATE: Please see the comments below, why this approach might not produce a stable result.
...
What is the difference between .*? and .* regular expressions?
...edy, first tries to match as many . as possible.
eeeAiiZuuuuAoooZeeee
\_______________/
A.* matched, Z can't match
Since the Z doesn't match, the engine backtracks, and .* must then match one fewer .:
eeeAiiZuuuuAoooZeeee
\______________/
A.* matched, Z still can't match
This ha...
Header files for x86 SIMD intrinsics
.../x86-64 use x86intrin.h
For gcc/clang/armcc targeting ARM with NEON use arm_neon.h
For gcc/clang/armcc targeting ARM with WMMX use mmintrin.h
For gcc/clang/xlcc targeting PowerPC with VMX (aka Altivec) and/or VSX use altivec.h
For gcc/clang targeting PowerPC with SPE use spe.h
You can handle all t...
How to get the parents of a Python class?
...
Use the following attribute:
cls.__bases__
From the docs:
The tuple of base classes of a class
object.
Example:
>>> str.__bases__
(<type 'basestring'>,)
Another example:
>>> class A(object):
... pass
...
>>> ...
iOS开发调试技巧总结 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...(format,...)do{\
fprintf(stderr,"%s\n",\
[[[NSStringstringWithUTF8String:__FILE__]lastPathComponent]UTF8String],\
__LINE__,__func__);\
(NSLog)((format),##__VA_ARGS__);\
fprintf(stderr,"-------\n");\
}while(0)
@interfaceViewController
@end
@implementationViewController
-(void)viewDi...
Finding the source code for built-in Python functions?
... particular module or function is implemented in you can usually print the __file__ attribute. Alternatively, you may use the inspect module, see the section Retrieving Source Code in the documentation of inspect.
For built-in classes and methods this is not so straightforward since inspect.getfile...
What does -> mean in Python function definitions?
...
And the information is available as a .__annotations__ attribute.
– Martijn Pieters♦
Jan 17 '13 at 13:06
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