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Zip lists in Python
...x. list, string, tuple, dictionary)
Output (list)
1st tuple = (element_1 of numbers, element_1 of letters)
2nd tuple = (e_2 numbers, e_2 letters)
…
n-th tuple = (e_n numbers, e_n letters)
List of n tuples: n is the length of the shortest argument (input)
len(numbers) =...
LINQ - Full Outer Join
...
I don't know if this covers all cases, logically it seems correct. The idea is to take a left outer join and right outer join then take the union of the results.
var firstNames = new[]
{
new { ID = 1, Name = "John" },
new { ID = 2, Name = "Sue"...
How do I use vim registers?
...on Windows (or from "mouse highlight" clipboard on Linux)
"*p
To access all currently defined registers type
:reg
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Run a callback only if an attribute has changed in Rails
...
Rails 5.1+
class Page < ActiveRecord::Base
before_save :do_something, if: :will_save_change_to_status_id?
private
def do_something
# ...
end
end
The commit that changed ActiveRecord::Dirty is here: https://github.com/rails/rails/commit/16ae3db5a5c6a08383b974ae...
How to have the cp command create any necessary folders for copying a file to a destination [duplica
... the mkdir/cp command above. It just creates a single level of folder. Actually I'm not sure when it can be useful.
– Penghe Geng
Apr 13 '15 at 14:30
...
How to read last commit comment?
...
Generally:
git log -n
will show you the last n commit messages
More elegantly - if you want a quick overview of your commits
git log --oneline -n
This will Show just the first line of the last n commit messages.
You can sa...
Is there a standard sign function (signum, sgn) in C/C++?
...T val) {
return (T(0) < val) - (val < T(0));
}
Benefits:
Actually implements signum (-1, 0, or 1). Implementations here using copysign only return -1 or 1, which is not signum. Also, some implementations here are returning a float (or T) rather than an int, which seems wasteful.
Works ...
Can Python print a function definition?
...pile a regular expression pattern, returning a pattern object."
return _compile(pattern, flags)
This will work in the interactive prompt, but apparently only on objects that are imported (not objects defined within the interactive prompt). And of course it will only work if Python can find th...
Should IBOutlets be strong or weak under ARC?
...t practice from Apple is for IBOutlets to be strong unless weak is specifically needed to avoid a retain cycle. As Johannes mentioned above, this was commented on in the "Implementing UI Designs in Interface Builder" session from WWDC 2015 where an Apple Engineer said:
And the last option I want...
What happens to a detached thread when main() exits?
..._local) variables of other threads nor static objects.
This appears to be allowed to allow thread managers as static objects (note in [basic.start.term]/4 says as much, thanks to @dyp for the pointer).
Problems arise when the destruction of static objects has finished, because then execution enter...