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How to remove items from a list while iterating?
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@Derek x = ['foo','bar','baz']; y = x; x = [item for item in x if determine(item)]; This reassigns x to the result of the list comprehension, but y still refers to the original list ['foo','bar','baz']. If you expected x and y to refer to...
How to cast/convert pointer to reference in C++
...can I pass a pointer ( Object *ob ) to a function which prototype is void foo(Object &) ?
2 Answers
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How do you set a default value for a MySQL Datetime column?
...at will update when the row is updated. The type definition:
CREATE TABLE foo (
`creation_time` DATETIME DEFAULT CURRENT_TIMESTAMP,
`modification_time` DATETIME ON UPDATE CURRENT_TIMESTAMP
)
Reference:
http://optimize-this.blogspot.com/2012/04/datetime-default-now-finally-available.ht...
How to count certain elements in array?
...rn this into a one-liner if you only need to count one value:
_.countBy(['foo', 'foo', 'bar'])['foo']; // 2
This also works fine on arrays of numbers. The one-liner for your example would be:
_.countBy([1, 2, 3, 5, 2, 8, 9, 2])[2]; // 3
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Ruby Hash to array of values
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There is also this one:
hash = { foo: "bar", baz: "qux" }
hash.map(&:last) #=> ["bar", "qux"]
Why it works:
The & calls to_proc on the object, and passes it as a block to the method.
something {|i| i.foo }
something(&:foo)
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How to read environment variables in Scala
...guration library is used (by default in Play2 and Akka) then you can use
foo = "default value"
foo = ${?VAR_NAME}
syntax to override foo if an environment variable VAR_NAME exist.
More details in https://github.com/typesafehub/config#optional-system-or-env-variable-overrides
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How do you access the matched groups in a JavaScript regular expression?
...arr[1]);
The \b isn't exactly the same thing. (It works on --format_foo/, but doesn't work on format_a_b) But I wanted to show an alternative to your expression, which is fine. Of course, the match call is the important thing.
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How to escape single quotes within single quoted strings
...uoted one, content on this string may be interprested by the shell: echo $'foo\'b!ar'=> !ar': event not found
– regilero
May 28 '14 at 15:22
3
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Does JavaScript guarantee object property order?
...r strings keys, and ascending order for number-like keys:
// key order: 1, foo, bar
const obj = { "foo": "foo", "1": "1", "bar": "bar" }
Using an array or a Map object can be a better way to achieve this. Map shares some similarities with Object and guarantees the keys to be iterated in order of in...
How can I change the current URL?
...Use the URL hash. For example, you can go from example.com to example.com#foo without loading a new page. You can simply set window.location.hash to make this easy. Then, you should listen to the HTML5 hashchange event, which will be fired when the user presses the back button. This is not suppo...