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Cocoa Core Data efficient way to count entities
...ke a count over an Entity-Type (like SQL can do with SELECT count(1) ...). Now I just solved this task with selecting all with NSFetchedResultsController and getting the count of the NSArray ! I am sure this is not the best way...
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Using Python's os.path, how do I go up one directory?
...
Using abspath will just clean it up a bit. If it's not there, the actual string for the path name will be /Users/hobbes3/Sites/mysite/mysite/../templates, which is perfectly fine, but just a little more cluttered. It also ensures that Django's reminder to use absolute...
How to copy an object in Objective-C
...lways with reference types, there are two notions of "copy". I'm sure you know them, but for completeness.
A bitwise copy. In this, we just copy the memory bit for bit - this is what NSCopyObject does. Nearly always, it's not what you want. Objects have internal state, other objects, etc, and ofte...
Using $_POST to get select option value from HTML
... Why is it always better to give values to your <option> tags? "If no value attribute is included, the value defaults to the text contained inside the element". If it works, what's wrong with that?
– osullic
Jan 8 '19 at 15:46
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Python Linked List
...bda lst, el: cons(el, lst), reversed(args), None)
car = lambda lst: lst[0] if lst else lst
cdr = lambda lst: lst[1] if lst else lst
nth = lambda n, lst: nth(n-1, cdr(lst)) if n > 0 else car(lst)
length = lambda lst, count=0: length(cdr(lst), count+1) if lst else count
begin = lambda *args: arg...
STL中map容器使用自定义key类型报错详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
...重载<操作符了：
bool operator<(const a& a1, const a& a2)
{
if ( a1.m_a>=a2.m_a )
return false;
return true;
}
编译OK，可以使用了。
结论
因此，通过重载<操作符可以使自定义结构支持map容器。
另外的一种方法
下面介...
Why do some functions have underscores “__” before and after the function name?
This "underscoring" seems to occur a lot, and I was wondering if this was a requirement in the Python language, or merely a matter of convention?
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Python: Is it bad form to raise exceptions within __init__?
Is it considered bad form to raise exceptions within __init__ ? If so, then what is the accepted method of throwing an error when certain class variables are initialized as None or of an incorrect type?
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How to apply a function to two columns of Pandas dataframe
...sing apply on the dataframe, which I am calling with axis = 1.
Note the difference is that instead of trying to pass two values to the function f, rewrite the function to accept a pandas Series object, and then index the Series to get the values needed.
In [49]: df
Out[49]:
0 ...
Windows 7, 64 bit, DLL problems
...risP said, the problem was in my project dependencies. The key is "How to know your project dependencies in Qt 5?".
As I didn't find any clear way to know it (Dependency Walker didn't help me a lot...), I followed next the "inverse procedure" that takes no more than 5 minutes and avoid a lot of he...