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Compelling examples of custom C++ allocators?
What are some really good reasons to ditch std::allocator in favor of a custom solution? Have you run across any situations where it was absolutely necessary for correctness, performance, scalability, etc? Any really clever examples?
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Apache Spark: map vs mapPartitions?
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I'm seeing the opposite -- even with very small operations, its faster to call mapPartitions and iterate than call map. I am assuming that this is just the overhead of starting the language engine that will process the map task. (I'm in R, which may have more startup...
PostgreSQL create table if not exists
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CREATE TABLE myschema.mytable (i integer);
END IF;
END
$func$;
Call:
SELECT create_mytable(); -- call as many times as you want.
Notes:
The columns schemaname and tablename in pg_tables are case-sensitive. If you double-quote identifiers in the CREATE TABLE statement, you need ...
Is the Scala 2.8 collections library a case of “the longest suicide note in history”? [closed]
...ith something like map or collect would be built in, and nobody has to see all the hoops the compiler has to go through to make them work smoothly. In Scala, it's all in a library, and therefore out in the open.
In fact the functionality of map that's supported by its complicated type is pretty adv...
How do you use bcrypt for hashing passwords in PHP?
...d salts (bcrypt REQUIRES salts) and you can be sure that an attack is virtually unfeasible without either ludicrous amount of funds or hardware.
bcrypt uses the Eksblowfish algorithm to hash passwords. While the encryption phase of Eksblowfish and Blowfish are exactly the same, the key schedule pha...
Why are regular expressions so controversial? [closed]
...ions. And not just slow, but the performance of the regex engine can be totally unpredictable when faced with arbitrary (user-supplied) inputs.
– Pacerier
Dec 1 '15 at 21:53
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iOS - Dismiss keyboard when touching outside of UITextField
...TapGestureRecognizer(target: self, action: #selector(self.dismissKeyboard (_:)))
self.view.addGestureRecognizer(tapGesture)
For dismissKeyboard
@objc func dismissKeyboard (_ sender: UITapGestureRecognizer) {
aTextField.resignFirstResponder()
}
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Java: int array initializes with nonzero elements
...here it is not. Such a behavior occurs first in JDK 7u4 and also occurs in all later updates (I use 64-bit implementation). The following code throws exception:
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Boost Statechart vs. Meta State Machine
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As there seems to be much interest, please allow me to give my (obviously biased) opinion, which should therefore be taken with a grain of salt:
MSM is much faster
MSM requires no RTTI or anything virtual
MSM has a more complete UML2 support (for example internal tr...
Install tkinter for Python
...: No module named 'tkinter' I Use(Python 3.7.5)
– sqp_125
Dec 9 '19 at 18:30
Solution: sudo apt-get install python3.7-...