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Lock, mutex, semaphore… what's the difference?
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A lock allows only one thread to enter the part that's locked and the lock is not shared with any other processes.
A mutex is the same as a lock but it can be system wide (shared by multiple processes).
A semaphore does the same as a mutex but allows x number of threads to enter, this...
Checking if a key exists in a JavaScript object?
...r, if you want to particularly test for properties of the object instance (and not inherited properties), use hasOwnProperty:
obj.hasOwnProperty("key") // true
For performance comparison between the methods that are in, hasOwnProperty and key is undefined, see this benchmark
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How to create a self-signed certificate with OpenSSL
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You can do that in one command:
openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365
You can also add -nodes (short for no DES) if you don't want to protect your private key with a passphrase. Otherwise it will prompt you for "...
Efficient way to apply multiple filters to pandas DataFrame or Series
I have a scenario where a user wants to apply several filters to a Pandas DataFrame or Series object. Essentially, I want to efficiently chain a bunch of filtering (comparison operations) together that are specified at run-time by the user.
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Equation (expression) parser with precedence?
...'ve developed an equation parser using a simple stack algorithm that will handle binary (+, -, |, &, *, /, etc) operators, unary (!) operators, and parenthesis.
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SQL Server query to find all permissions/access for all users in a database
...a specific database, or objects within the database such as tables, views, and stored procedures, either directly or due to roles, etc. This report would be used for security auditing purposes. Not sure if anyone has a query that will fit my needs completely, but hopefully something that will give...
REST Complex/Composite/Nested Resources [closed]
...is slightly more complex in that a cover really does require a comic book, and visa versa.
However, if you consider an email message as a resource, and the from address as a child resource, you can obviously still reference the from address separately. For example, get all from addresses. Or, creat...
How do I completely uninstall Node.js, and reinstall from beginning (Mac OS X)
My version of node is always v0.6.1-pre even after I install brew node and NVM install v0.6.19.
28 Answers
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Why em instead of px?
I heard you should define sizes and distances in your stylesheet with em instead of in pixels. So the question is why should I use em instead of px when defining styles in css? Is there a good example that illustrates this?
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How to make good reproducible pandas examples
Having spent a decent amount of time watching both the r and pandas tags on SO, the impression that I get is that pandas questions are less likely to contain reproducible data. This is something that the R community has been pretty good about encouraging, and thanks to guides like this , newc...