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What's the difference between parenthesis $() and curly bracket ${} syntax in Makefile?
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The ${} style lets you test the make rules in the shell, if you have the corresponding environment variables set, since that is compatible with bash.
share
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xtree(1796): warning C4800: “int”: 将值强制为布尔值“true”或“false...
...e\xtree(1775): 参见对正在编译的函数 模板 实例化“std::pair<_Ty1,_Ty2> std::_Tree<_Traits>::_Insert_nohint<std::pair<const _Kty,_Ty>&,_Nodety>(bool,_Valty,_Nodety)”的引用
1> with
1> [
1> _Ty1=std::_Tree_iterator<std::_Tree_val<std::_Tree_simple_t...
Is a memory leak created if a MemoryStream in .NET is not closed?
...possible to change the internal implementation (e.g. when mocking for unit testing).
You then will need be in trouble if you haven't used Dispose in your bar implementation:
void bar()
{
using (Stream s = foo())
{
// do stuff with s
return;
}
}
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What is the __del__ method, How to call it?
I am reading a code. There is a class in which __del__ method is defined. I figured out that this method is used to destroy an instance of the class. However, I cannot find a place where this method is used. The main reason for that is that I do not know how this method is used, probably not like ...
Should __init__() call the parent class's __init__()?
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In Python, calling the super-class' __init__ is optional. If you call it, it is then also optional whether to use the super identifier, or whether to explicitly name the super class:
object.__init__(self)
In case of object, calling the super method is not st...
Is there a Python caching library?
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From Python 3.2 you can use the decorator @lru_cache from the functools library.
It's a Last Recently Used cache, so there is no expiration time for the items in it, but as a fast hack it's very useful.
from functools import lru_cache
@lru_cache(maxsize=256)
def f(x):
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Inverse dictionary lookup in Python
...s slow as yours, because it creates a list from the dict twice.
key = dict_obj.keys()[dict_obj.values().index(value)]
Or if you prefer brevity over readability you can save one more character with
key = list(dict_obj)[dict_obj.values().index(value)]
And if you prefer efficiency, @PaulMcGuire's...
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...
Is there a built-in function to print all the current properties and values of an object?
So what I'm looking for here is something like PHP's print_r function.
25 Answers
25...
Purpose of Python's __repr__
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__repr__ should return a printable representation of the object, most likely one of the ways possible to create this object. See official documentation here. __repr__ is more for developers while __str__ is for end users.
A ...