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Difference between . and : in Lua
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To be completely precise, obj:method(1, 2, 3) is the same as
do
local _obj = obj
_obj.method(_obj, 1, 2, 3)
end
Why the local variable? Because, as many have pointed out, obj:method() only indexes _ENV once to get obj. This normally just important when considering speed, but consider this s...
How do you mock out the file system in C# for unit testing?
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Edit: Install the NuGet package System.IO.Abstractions.
This package did not exist when this answer was originally accepted. The original answer is provided for historical context below:
You could do it by creating an interface:
inter...
Trim spaces from end of a NSString
...substringWithRange:NSMakeRange(location, i - location)];
}
So now just call it. Supposing you have a string that has spaces on the front and spaces on the end and you just want to remove the spaces on the end, you can call it like this:
NSString *oneTwoThree = @" TestString ";
NSString *resul...
PostgreSQL: How to pass parameters from command line?
...command line (outside the script). I want to avoid going in and replacing all the ? with actual values, instead I'd like to pass the arguments after the query.
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How to find keys of a hash?
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There is function in modern JavaScript (ECMAScript 5) called Object.keys performing this operation:
var obj = { "a" : 1, "b" : 2, "c" : 3};
alert(Object.keys(obj)); // will output ["a", "b", "c"]
Compatibility details can be found here.
On the Mozilla site there is also a sn...
In JavaScript, why is “0” equal to false, but when tested by 'if' it is not false by itself?
...e special [[Get]] internal method defined below.
b. Return the result of calling the get internal method using base as its this value, and passing
GetReferencedName(V) for the argument
Or in other words, a string has a primitive base, which calls back the internal get method and ends up looking ...
Sleep for milliseconds
... facilities:
#include <chrono>
#include <thread>
std::this_thread::sleep_for(std::chrono::milliseconds(x));
Clear and readable, no more need to guess at what units the sleep() function takes.
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select、poll、epoll之间的区别总结[整理] - C/C++ - 清泛网 - 专注C/C++及内核技术
...1、select实现
select的调用过程如下所示：
（1）使用copy_from_user从用户空间拷贝fd_set到内核空间
（2）注册回调函数__pollwait
（3）遍历所有fd，调用其对应的poll方法（对于socket，这个poll方法是sock_poll，sock_poll根据情况会调用到...
How do I create a file and write to it in Java?
...te that each of the code samples below may throw IOException. Try/catch/finally blocks have been omitted for brevity. See this tutorial for information about exception handling.
Note that each of the code samples below will overwrite the file if it already exists
Creating a text file:
PrintWriter...
How to export table as CSV with headings on Postgresql?
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COPY products_273 TO '/tmp/products_199.csv' WITH (FORMAT CSV, HEADER);
as described in the manual.
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