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Python hashable dicts
...another dictionary for obvious reasons.
class hashabledict(dict):
def __hash__(self):
return hash(tuple(sorted(self.items())))
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Why does += behave unexpectedly on lists?
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The general answer is that += tries to call the __iadd__ special method, and if that isn't available it tries to use __add__ instead. So the issue is with the difference between these special methods.
The __iadd__ special method is for an in-place addition, that is it mut...
List directory tree structure in python?
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Here's a function to do that with formatting:
import os
def list_files(startpath):
for root, dirs, files in os.walk(startpath):
level = root.replace(startpath, '').count(os.sep)
indent = ' ' * 4 * (level)
print('{}{}/'.format(indent, os.path.basename(root)))
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How to implement a good __hash__ function in python [duplicate]
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__hash__ should return the same value for objects that are equal. It also shouldn't change over the lifetime of the object; generally you only implement it for immutable objects.
A trivial implementation would be to just ret...
使用std::string作为std::map的key出错解决 - C/C++ - 清泛网 - 专注C/C++及内核技术
...0\vc\include\xstddef(180): error C2784: “bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)”: 未能从“const std::string”为“const std::_Tree<_Traits> &”推导 模板 参数
1> c:\program files (x86)\microsoft visual studio 11.0\vc\include\xtree(2245...
String concatenation in Ruby
...; but that is not the usual way
With string interpolation
source = "#{ROOT_DIR}/#{project}/App.config"
with +
source = "#{ROOT_DIR}/" + project + "/App.config"
The second method seems to be more efficient in term of memory/speed from what I've seen (not measured though). All three methods will...
Object of custom type as dictionary key
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You need to add 2 methods, note __hash__ and __eq__:
class MyThing:
def __init__(self,name,location,length):
self.name = name
self.location = location
self.length = length
def __hash__(self):
return hash((self.name...
Catching an exception while using a Python 'with' statement
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from __future__ import with_statement
try:
with open( "a.txt" ) as f :
print f.readlines()
except EnvironmentError: # parent of IOError, OSError *and* WindowsError where available
print 'oops'
If you want differ...
How does Python's super() work with multiple inheritance?
...including two earlier attempts).
In your example, Third() will call First.__init__. Python looks for each attribute in the class's parents as they are listed left to right. In this case, we are looking for __init__. So, if you define
class Third(First, Second):
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Python will start by looki...
How can I swap positions of two open files (in splits) in vim?
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Starting with this:
____________________
| one | two |
| | |
| |______|
| | three|
| | |
|___________|______|
Make 'three' the active window, then issue the command ctrl+w J. This moves ...