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Why use Abstract Base Classes in Python?
...emented classes.
Long version
There is a contract between a class and its callers. The class promises to do certain things and have certain properties.
There are different levels to the contract.
At a very low level, the contract might include the name of a method or its number of parameters.
In a s...
Convert objective-c typedef to its string equivalent
...
This is really a C question, not specific to Objective-C (which is a superset of the C language). Enums in C are represented as integers. So you need to write a function that returns a string given an enum value. There are many ways to...
How to “properly” create a custom object in JavaScript?
...e result is that in mixed company you will have a mishmash of metaclasses, all behaving slightly differently. What's worse, most JavaScript tutorial material is terrible and serves up some kind of in-between compromise to cover all bases, leaving you very confused. (Probably the author is also confu...
C library function to perform sort
...
qsort() is the function you're looking for. You call it with a pointer to your array of data, the number of elements in that array, the size of each element and a comparison function.
It does its magic and your array is sorted in-place. An example follows:
#include <st...
搭建高可用mongodb集群（二）—— 副本集 - 大数据 & AI - 清泛网 - 专注C/...
...(config);
#输出成功
{
"info" : "Config now saved locally. Should come online in about a minute.",
"ok" : 1
}
#查看日志，副本集启动成功后，138为主节点PRIMARY，136、137为副本节点SECONDARY。
Sun Dec 29 20:26:13.842 [conn3] replSet repl...
Writing your own STL Container
...or_tag,std::random_access_iterator_tag. Also note that the below is technically more strict than required, but this is the idea. Note that the vast majority of the "standard" functions are technically optional, due to the awesomeness that is iterators.
template <class T, class A = std::allocator...
Rails check if yield :area is defined in content_for
...
not really necessary to create a helper method:
<% if @content_for_sidebar %>
<div id="sidebar">
<%= yield :sidebar %>
</div>
<% end %>
then of course in your view:
<% content_for :sideb...
How to calculate a time difference in C++
...turns the CPU time consumed by the program. So if the program is run in parallel the time returned by the function would be the accumulated of the time spent on all CPUs, rather than the time elapsed cplusplus.com/reference/ctime/clock
– Ameer Jewdaki
Aug 3 '1...
How to easily map c++ enums to strings
...xtra syntactic sugar, here's how to write a map_init class. The goal is to allow
std::map<MyEnum, const char*> MyMap;
map_init(MyMap)
(eValue1, "A")
(eValue2, "B")
(eValue3, "C")
;
The function template <typename T> map_init(T&) returns a map_init_helper<T>.
map...
M_PI works with math.h but not with cmath in Visual Studio
...) and suddenly it compile perfectly.
Try moving it higher up the page. Totally unsure as to why this would cause issues though.
Edit: Figured it out. The #include <math.h> occurs within cmath's header guards. This means that something higher up the list of #includes is including cmath with...