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How does the “this” keyword work?
...ains in JavaScript.
Once you start getting used to this, the rules are actually pretty simple. The ECMAScript 5.1 Standard defines this:
§11.1.1 The this keyword
The this keyword evaluates to the value of the ThisBinding of the current execution context
ThisBinding is something that the JavaScrip...
Recursive Lock (Mutex) vs Non-Recursive Lock (Mutex)
POSIX allows mutexes to be recursive. That means the same thread can lock the same mutex twice and won't deadlock. Of course it also needs to unlock it twice, otherwise no other thread can obtain the mutex. Not all systems supporting pthreads also support recursive mutexes, but if they want to be P...
Is there a performance gain in using single quotes vs double quotes in ruby?
...t waste your time.
Actual interpolation is a different story, of course. 'foo' will be almost exactly 1 second faster than "#{sleep 1; nil}foo".
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How to add reference to a method parameter in javadoc?
...ding the docs for javadoc there is no such feature.
Don't use <code>foo</code> as recommended in other answers; you can use {@code foo}. This is especially good to know when you refer to a generic type such as {@code Iterator<String>} -- sure looks nicer than <code>Iterator...
sed: print only matching group
...uses the entire line to be replaced with the contents of the group
echo "foo bar <foo> bla 1 2 3.4" |
sed -n 's/.*\([0-9][0-9]*[\ \t][0-9.]*[ \t]*$\)/\1/p'
2 3.4
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Object-orientation in C
... describes it.
Exception in C is a C89 implementation of the TRY-CATCH-FINALLY found in other OO languages. It comes with a testsuite and some examples.
Both by Laurent Deniau, which is working a lot on OOP in C.
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How do I get the parent directory in Python?
...that does nothing but string manipulation. To verify if the pathname actually exist requires a disk access. Depends on the application this may or may not be desirable.
– Wai Yip Tung
May 18 '10 at 19:45
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Overload constructor for Scala's Case Classes?
...
Overloading constructors isn't special for case classes:
case class Foo(bar: Int, baz: Int) {
def this(bar: Int) = this(bar, 0)
}
new Foo(1, 2)
new Foo(1)
However, you may like to also overload the apply method in the companion object, which is called when you omit new.
object Foo {
d...
How do I return early from a rake task?
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A Rake task is basically a block. A block, except lambdas, doesn't support return but you can skip to the next statement using next which in a rake task has the same effect of using return in a method.
task :foo do
puts "printed"
next
put...
Matching an empty input box using CSS
...e present in the input tag. Tested in Chrome - not sure if this counts for all browsers.
– Berend
Mar 17 '17 at 6:23
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