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What is the session's “secret” option?
...ething like topsecret. The secret should be a random string of characters. Ideally you would also change it periodically in case it has been discovered. However, this requires support for secret rotation so you don't immediately invalidate existing sessions. That is, two session secrets should be co...
How can I know when an EditText loses focus?
...catch when an EditText loses focus, I've searched other questions but I didn't find an answer.
5 Answers
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Mysql: Select rows from a table that are not in another
...o the subselect based on a column name, not *.
For example, if you had an id field common to both tables, you could do:
SELECT * FROM Table1 WHERE id NOT IN (SELECT id FROM Table2)
Refer to the MySQL subquery syntax for more examples.
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how to disable DIV element and everything inside [duplicate]
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disabled isn't a valid property for div.
– James Donnelly
Mar 21 '13 at 18:34
17
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Is it possible to make a type only movable and not copyable?
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Preface: This answer was written before opt-in built-in traits—specifically the Copy aspects—were implemented. I've used block quotes to indicate the sections that only applied to the old scheme (the one that applied when the question was asked).
Old: To answer the basic question, you c...
Hidden Features of Java
...hen I first discovered it, never heard of it before.
ThreadLocals are typically not so widely known as a way to store per-thread state.
Since JDK 1.5 Java has had extremely well implemented and robust concurrency tools beyond just locks, they live in java.util.concurrent and a specifically interes...
Difference between ref and out parameters in .NET [duplicate]
...out x); // OK
int y;
Foo(ref y); // Error: y should be initialized before calling the method
Ref parameters are for data that might be modified, out parameters are for data that's an additional output for the function (eg int.TryParse) that are already using the return value for something.
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STAThread and multithreading
...eading is a COM concept; if you're not using COM, and none of the APIs you call use COM "under the covers", then you don't need to worry about apartments.
If you do need to be aware of apartments, then the details can get a little complicated; a probably-oversimplified version is that COM objects t...
Why would I ever use push_back instead of emplace_back?
...e between these two statements is that the more powerful emplace_back will call any type of constructor out there, whereas the more cautious push_back will call only constructors that are implicit. Implicit constructors are supposed to be safe. If you can implicitly construct a U from a T, you are s...
Is there a difference between copy initialization and direct initialization?
...s expression is initialized to (loosely speaking) in C++17. These objects (called "result objects") are the variables created by a declaration (like a1), artificial objects created when the initialization ends up being discarded, or if an object is needed for reference binding (like, in A_factory_fu...