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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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Is there any way to kill a Thread?
...other threads that must be killed as well.
The nice way of handling this if you can afford it (if you are managing your own threads) is to have an exit_request flag that each threads checks on regular interval to see if it is time for it to exit.
For example:
import threading
class StoppableThr...
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...
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...
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...
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...