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What does Python's eval() do?
...s such brought a level of protection into our system. At this point we can start to add back in functions that we do want exposed.
>>>from os import cpu_count
>>>exposed_methods = {'cpu_count': cpu_count}
>>>eval('cpu_count()', {'__builtins__':None}, exposed_methods)
8
&g...
Copying files from Docker container to host
... to STDOUT. This is similar to docker run -d except the container is never started.
So, you can do:
docker create -ti --name dummy IMAGE_NAME bash
docker cp dummy:/path/to/file /dest/to/file
docker rm -f dummy
Here, you never start the container. That looked beneficial to me.
...
Exploring Docker container's file system
...ndex - you don't have a clue what the image contains so it's impossible to start the application.
26 Answers
...
How do you fix a bad merge, and replay your good commits onto a fixed merge?
...mit --amend --no-edit
# Rebase your previous branch onto this new commit, starting from the old-commit
git rebase --preserve-merges --onto temp <old-commit> master
# Verify your changes
git diff master@{1}
Solution 3: Non-interactive Rebase
This will work if you just want to remove a co...
How to get current time and date in C++?
...
#include <chrono>
#include <ctime>
int main()
{
auto start = std::chrono::system_clock::now();
// Some computation here
auto end = std::chrono::system_clock::now();
std::chrono::duration<double> elapsed_seconds = end-start;
std::time_t end_time = std::chr...
How to update a plot in matplotlib?
...stack of frames, instead of generating and using contours on the fly.
Starting with a 3D array of images of shape (nBins, nBins, nBins), called frames.
def animate_frames(frames):
nBins = frames.shape[0]
frame = frames[0]
tempCS1 = plt.imshow(frame, cmap=plt.cm.gray)
for k ...
Which Java Collection should I use?
...e most part. However Java LinkedList is a double linked list, so access at start and at end are both fast. You will note that of the branches above all three questions have to answer yes before I'd recommend using the LinkedList - so in other words I agree with you that in most cases the answer is n...
Ruby: Can I write multi-line string with no concatenation?
...e the .gsub invocation, in that case (although it might depend on both the starting indentation and your final needs).
EDIT: Adding one more:
p %{
SELECT * FROM users
ORDER BY users.id DESC
}.gsub(/\s+/, " ").strip
# >> "SELECT * FROM users ORDER BY users.id DESC"
...
How to atomically delete keys matching a pattern using Redis
...
Starting with redis 2.6.0, you can run lua scripts, which execute atomically. I have never written one, but I think it would look something like this
EVAL "return redis.call('del', unpack(redis.call('keys', ARGV[1])))" 0 pre...
How can I use “sizeof” in a preprocessor macro?
... PAGE_SIZE; otherwise they will produce a compile-time error.
1. C11 way
Starting with C11 you can use static_assert (requires #include <assert.h>).
Usage:
static_assert(sizeof(someThing) == PAGE_SIZE, "Data structure doesn't match page size");
2. Custom macro
If you just want to get a ...