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What does the exclamation mark do before the function?
...
JavaScript syntax 101. Here is a function declaration:
function foo() {}
Note that there's no semicolon: this is just a function declaration. You would need an invocation, foo(), to actually run the function.
Now, when we add the seemingly innocuous exclamation mark: !function foo() {}...
var functionName = function() {} vs function functionName() {}
...ry, if, switch, while, etc., like this:
if (someCondition) {
function foo() { // <===== HERE THERE
} // <===== BE DRAGONS
}
And since they're processed before step-by-step code is run, it's tricky to know what to do when they're in a control structure.
Although...
How do you assert that a certain exception is thrown in JUnit 4 tests?
...t can use JUnit 4.7, you can use the ExpectedException Rule:
public class FooTest {
@Rule
public final ExpectedException exception = ExpectedException.none();
@Test
public void doStuffThrowsIndexOutOfBoundsException() {
Foo foo = new Foo();
exception.expect(IndexOutOfBoundsExcepti...
How to get method parameter names?
... and **kwargs variables, and the defaults provided. ie.
>>> def foo(a, b, c=4, *arglist, **keywords): pass
>>> inspect.getfullargspec(foo)
(['a', 'b', 'c'], 'arglist', 'keywords', (4,))
Note that some callables may not be introspectable in certain implementations of Python. For...
Prepend a level to a pandas MultiIndex
...ne line using pandas.concat():
import pandas as pd
pd.concat([df], keys=['Foo'], names=['Firstlevel'])
An even shorter way:
pd.concat({'Foo': df}, names=['Firstlevel'])
This can be generalized to many data frames, see the docs.
...
Is there a literal notation for an array of symbols?
...
Yes! This is possible now in Ruby 2.0.0. One way to write it is:
%i{foo bar} # => [:foo, :bar]
You can also use other delimiters, so you could also write %i(foo bar) or %i!foo bar! for example.
This feature was originally announced here:
http://www.ruby-lang.org/zh_TW/news/2012/11/02/...
PHP: How to handle
...</content>'
);
echo (string) $content;
// or with parent element:
$foo = simplexml_load_string(
'<foo><content><![CDATA[Hello, world!]]></content></foo>'
);
echo (string) $foo->content;
You might have better luck with LIBXML_NOCDATA:
$content = simpl...
Return a `struct` from a function in C
...
When making a call such as a = foo();, the compiler might push the address of the result structure on the stack and passes it as a "hidden" pointer to the foo() function. Effectively, it could become something like:
void foo(MyObj *r) {
struct MyObj a...
Get specific object by id from array of objects in AngularJS
...dded in arrays. So assuming the same collection, the solution'd be:
const foo = { "results": [
{
"id": 12,
"name": "Test"
},
{
"id": 2,
"name": "Beispiel"
},
{
"id": 3,
"name": "Sample"
}
] };
foo.results.find(item => item.i...
Understanding the difference between Object.create() and new SomeFunction()
... property descriptors argument:
var o = Object.create({inherited: 1}, {
foo: {
get: (function () { // a closure
var closured = 'foo';
return function () {
return closured+'bar';
};
})()
}
});
o.foo; // "foobar"
Note that I'm talking about the ECMAScript 5th ...