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What is a elegant way in Ruby to tell if a variable is a Hash or an Array?
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@some_var.is_a?(Hash)
It's worth noting that the "is_a?" method is true if the class is anywhere in the objects ancestry tree. for instance:
@some_var.is_a?(Object) # => true
the above is true if @some_var is an instance of a hash or other class that stems from Object. So, if you want a st...
Remove all values within one list from another list? [duplicate]
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>>> a = range(1, 10)
>>> [x for x in a if x not in [2, 3, 7]]
[1, 4, 5, 6, 8, 9]
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What happens if a finally block throws an exception?
If a finally block throws an exception, what exactly happens?
11 Answers
11
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When to throw an exception?
...a function which is supposed to examine an arbitrary class and return true if that class inherits from List<>. This function asks the question, "Is this object a descendant of List?" This function should never throw an exception, because there are no gray areas in its operation - every single ...
Quick-and-dirty way to ensure only one instance of a shell script is running at a time
...that uses a lockfile and echoes a PID into it. This serves as a protection if the process is killed before removing the pidfile:
LOCKFILE=/tmp/lock.txt
if [ -e ${LOCKFILE} ] && kill -0 `cat ${LOCKFILE}`; then
echo "already running"
exit
fi
# make sure the lockfile is removed when w...
Check if current directory is a Git repository
...rg.uk/).
# Distributed under the GNU General Public License, version 2.0.
if [ -d .git ]; then
echo .git;
else
git rev-parse --git-dir 2> /dev/null;
fi;
You could either wrap that in a function or use it in a script.
Condensed into a one line condition suitable for bash and zsh
[ -d .git...
Return type of '?:' (ternary conditional operator)
...alue or an rvalue. This is its value category. (This is somewhat of a simplification, in C++11 we have lvalues, xvalues and prvalues.)
In very broad and simple terms, an lvalue refers to an object in memory and an rvalue is just a value that may not necessarily be attached to an object in memory.
An...
How to do if-else in Thymeleaf?
What's the best way to do a simple if - else in Thymeleaf?
10 Answers
10
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Delete all but the most recent X files in bash
...d globbing.
inability to distinguish between files and directories (i.e., if directories happened to be among the 5 most recently modified filesystem items, you'd effectively retain fewer than 5 files, and applying rm to directories will fail).
wnoise's answer addresses these issues, but the solu...
I want to remove double quotes from a String
...console.log(someStr.replace(/['"]+/g, ''));
That should do the trick... (if your goal is to replace all double quotes).
Here's how it works:
['"] is a character class, matches both single and double quotes. you can replace this with " to only match double quotes.
+: one or more quotes, chars, a...