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理解Python的 with 语句With语句是什么？Python’s with statement provides a very convenient way of dealing with the situation where you
With语句是什么？
Python’s with statement provides a very convenient way of dealing with the situation where you have to do a setup an...
How to implement a good __hash__ function in python [duplicate]
When implementing a class with multiple properties (like in the toy example below), what is the best way to handle hashing?
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How do I get the path and name of the file that is currently executing?
...iles but I need to get the filepath of the file that is currently running within the process.
29 Answers
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How can I get the version defined in setup.py (setuptools) in my package?
...file's contents in setup.py.
You could make a version.py in your package with a __version__ line, then read it from setup.py using execfile('mypackage/version.py'), so that it sets __version__ in the setup.py namespace.
If you want a much simpler way that will work with all Python versions and eve...
Evaluating a mathematical expression in a string
...hematical expressions. In particular, fourFn.py
shows how to parse basic arithmetic expressions. Below, I've rewrapped fourFn into a numeric parser class for easier reuse.
from __future__ import division
from pyparsing import (Literal, CaselessLiteral, Word, Combine, Group, Optional,
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Absolute vs relative URLs
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In general, it is considered best-practice to use relative URLs, so that your website will not be bound to the base URL of where it is currently deployed. For example, it will be able to work on localhost, as well as on your public domai...
How to set the prototype of a JavaScript object that has already been instantiated?
...have an object foo in my JavaScript code. foo is a complex object and it is generated somewhere else. How can I change the prototype of the foo object?
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What does “mro()” do?
...gt;, <type 'object'>)
>>>
As long as we have single inheritance, __mro__ is just the tuple of: the class, its base, its base's base, and so on up to object (only works for new-style classes of course).
Now, with multiple inheritance...:
>>> class D(B, C): pass
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>&...
Python hashable dicts
...are invalid, unless I also store the current version of the grammar along with the cached parse results. ( EDIT : a consequence of this use of key-value collections is that they should be immutable, but I don't intend to expose the interface to allow them to be changed, so either mutable or immutab...
difference between variables inside and outside of __init__()
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Variable set outside __init__ belong to the class. They're shared by all instances.
Variables created inside __init__ (and all other method functions) and prefaced with self. belong to the object instance.
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