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What is the difference between `after_create` and `after_save` and when to use which?

... readers should note that, according to the docs, ActiveRecord's update_all does not invoke any callbacks, including after_* – user2426679 Jan 10 at 19:34 add a comment ...
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return statement vs exit() in main()

Should I use exit() or just return statements in main() ? Personally I favor the return statements because I feel it's like reading any other function and the flow control when I'm reading the code is smooth (in my opinion). And even if I want to refactor the main() function, having return...
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How do I get the current time zone of MySQL?

...ng the web server and the DB server it's talking to are set to [if not actually in] the same timezone isn't a huge leap.) But beware that (as with MySQL), you can set the timezone that PHP uses (date_default_timezone_set), which means it may report a different value than the OS is using. If you're i...
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Join strings with a delimiter only if strings are not null or empty

... .filter(Boolean) (which is the same as .filter(x => x)) removes all "falsy" values (nulls, undefineds, empty strings etc). If your definition of "empty" is different, then you'll have to provide it, for example: [...].filter(x => typeof x === 'string' && x.length > 0) wi...
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How does a language expand itself? [closed]

...onality. In the case of e.g. Windows the operating system exposes the so-called WIN32 API for applications running on Windows. The Qt library uses that API to provide applications using Qt to its own API. You use Qt, Qt uses WIN32, WIN32 uses lower levels of the Windows operating system, and so on ...
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How do you increase the max number of concurrent connections in Apache?

...ts 200 MinSpareThreads 25 MaxSpareThreads 75 ThreadsPerChild 25 First of all, whenever an apache is started, it will start 2 child processes which is determined by StartServers parameter. Then each process will start 25 threads determined by ThreadsPerChild parameter so this means 2 process can se...
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Git interactive rebase no commits to pick

... pushed for your second question: have a branch with your changes (basically a configuration branch) and regularly merge the other branches into it. this way the changes will not move to other branches share | ...
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In c++ what does a tilde “~” before a function name signify?

... memory, etc. etc. Here's a description from ibm.com: Destructors are usually used to deallocate memory and do other cleanup for a class object and its class members when the object is destroyed. A destructor is called for a class object when that object passes out of scope or is explicitly delete...
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In Firebase, is there a way to get the number of children of a node without loading all the node dat

...a transaction secure though? It seems it could be easily hacked to artificially increase counts. This could be bad for voting systems. – Soviut Apr 7 '14 at 6:10 16 ...
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using jquery $.ajax to call a PHP function

This may be a simple answer, but I'm using jQuery's $.ajax to call a PHP script. What I want to do is basically put that PHP script inside a function and call the PHP function from javascript. ...