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Common use-cases for pickle in Python
...hon data over a TCP connection in a multi-core or distributed system (marshalling)
3) storing python objects in a database
4) converting an arbitrary python object to a string so that it can be used as a dictionary key (e.g. for caching & memoization).
There are some issues with the last one ...
How to make an image center (vertically & horizontally) inside a bigger div [duplicate]
...
Personally, I'd place it as the background image within the div, the CSS for that being:
#demo {
background: url(bg_apple_little.gif) no-repeat center center;
height: 200px;
width: 200px;
}
(Assumes a div with id="de...
What's the correct way to communicate between controllers in AngularJS?
...ms as raised by @numan. That is because the event will bubble down through all scopes.
However, the latter (using $rootScope.$emit + $rootScope.$on) does not suffer from this and can therefore be used as a fast communication channel!
From the angular documentation of $emit:
Dispatches an even...
How to post JSON to a server using C#?
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Don't build JSON manually. It is easy to make mistakes that allow for JSON injection.
– Florian Winter
Feb 27 '17 at 14:08
5
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Get first key in a (possibly) associative array?
...
2019 Update
Starting from PHP 7.3, there is a new built in function called array_key_first() which will retrieve the first key from the given array without resetting the internal pointer. Check out the documentation for more info.
You can use reset and key:
reset($array);
$first_key = key(...
rsync: how can I configure it to create target directory on server?
...er than the file, at the endpoint you provide on the server. Normally /tmp/foo/bar/file.c to remote:/tmp would produce remote:/tmp/file.c but with -R it creates /tmp/foo/bar/file.c Don't use this option unless you know what you are doing, you will get a really messy directory structure.
...
How to find Unused Amazon EC2 Security groups
...AWS CLI tool, I found an easy way to get what I need:
First, get a list of all security groups
aws ec2 describe-security-groups --query 'SecurityGroups[*].GroupId' --output text | tr '\t' '\n'
Then get all security groups tied to an instance, then piped to sort then uniq:
aws ec2 describe-instance...
Is there any haskell function to concatenate list with separator?
...gonkai Not sure what exactly you're referring to, but yes, these functions all allow arbitrary strings as both the separator and the elements. For example, intercalate "," ["some", "", "string"] = "some,,string" and intercalate "" ["foo", "bar"] = "foobar"
– Niklas B.
...
What does “while True” mean in Python?
...e loop body indefinitely. It's an idiom that you'll just get used to eventually! Most languages you're likely to encounter have equivalent idioms.
Note that most languages usually have some mechanism for breaking out of the loop early. In the case of Python it's the break statement in the cmd == 'e...
How to test an SQL Update statement before running it?
...verflow.com/a/18499823/1416909
):
# do some stuff that should be conditionally rollbacked later on
SET @v1 := UPDATE MyGuests SET lastname='Doe' WHERE id=2;
IF(v1 < 1) THEN
ROLLBACK;
ELSE
COMMIT;
END IF;
But I would suggest to use the language wrappers available in your favorite progr...