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Hidden Features of Java
...d it, never heard of it before.
ThreadLocals are typically not so widely known as a way to store per-thread state.
Since JDK 1.5 Java has had extremely well implemented and robust concurrency tools beyond just locks, they live in java.util.concurrent and a specifically interesting example is the j...
How to encrypt/decrypt data in php?
...= openssl_random_pseudo_bytes($key_size, $strong);
// $strong will be true if the key is crypto safe
This can be done once or multiple times (if you wish to create a chain of encryption keys). Keep these as private as possible.
IV
The initialisation vector adds randomness to the encryption and r...
How to convert Set to Array?
....forEach(v => array.push(v));
Previously, using the non-standard, and now deprecated array comprehension syntax:
let array = [v for (v of mySet)];
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Is “else if” a single keyword?
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They are not a single keyword if we go to the draft C++ standard section 2.12 Keywords table 4 lists both if and else separately and there is no else if keyword. We can find a more accessible list of C++ keywords by going to cppreferences section on keyw...
Any way to delete in vim without overwriting your last yank? [duplicate]
...in the registers:
"_dd
See also :help registers.
It's probably safest, if you want to paste something over and over again, to yank it into a "named" register.
"aY
Yanks a line into the a register. Paste it with "ap.
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How can jQuery deferred be used?
...he best use case I can think of is in caching AJAX responses. Here's a modified example from Rebecca Murphey's intro post on the topic:
var cache = {};
function getData( val ){
// return either the cached value or jqXHR object wrapped Promise
return $.when(
cache[ val ] ||
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Insert HTML with React Variable Statements (JSX)
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How does this work if you need to add something to <head>?
– Danielle Madeley
Oct 30 '15 at 3:37
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How to output in CLI during execution of PHP Unit tests?
...t (or conf file has beStrictAboutOutputDuringTests="true") - documentation now says "A test that emits output, for instance by invoking print in either the test code or the tested code, will be marked as risky when this check is enabled." phpunit.readthedocs.io/en/8.4/risky-tests.html#risky-tests
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Allowed characters in Linux environment variable names
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@checksum, UPPERCASE is explicitly specified for variable names with meaning to POSIX-specified tools, including the shell; names with at least one lower-case character are explicitly reserved for application use. Thus, best practice is actually to include at leas...
sqlalchemy IS NOT NULL select
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The other answer is the preferred answer now; it also avoids many IDEs including PyCharm from generating warnings.
– Antti Haapala
Oct 6 '16 at 7:21
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