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How do I implement a callback in PHP?
... be called directly
$cb2 = 'ClassName::someStaticMethod';
$cb2(); // fatal error
// legacy syntax for PHP 4
$cb3 = array(&$object, 'somePublicMethod');
This is a safe way to use callable values in general:
if (is_callable($cb2)) {
// Autoloading will be invoked to load the class "ClassNa...
Pointer arithmetic for void pointer in C
... MSVC) disallow arithmetic on void*, and GCC disallows it if the -pedantic-errors flag is specified, or if the -Werror-pointer-arith flag is specified (this flag is useful if your code base must also compile with MSVC).
The C Standard Speaks
Quotes are taken from the n1256 draft.
The standard's d...
Unix command to find lines common in two files
...ve the temporary files afterwards, and cope with cleaning up in case of an error. In many scenarios, the process substitution will also be a lot quicker because you can avoid the disk I/O as long as the results fit into memory.
– tripleee
Dec 8 '17 at 5:41
...
System.Security.SecurityException when writing to Event Log
...
This answer describes the real reason behind the error. The check exists tries to enumerate the whole key. if it exists, checkExists works fine.
– DanO
Jul 29 '15 at 16:40
...
Check to see if python script is running
...bind('\0' + process_name)
print 'I got the lock'
except socket.error:
print 'lock exists'
sys.exit()
get_lock('running_test')
while True:
time.sleep(3)
It is atomic and avoids the problem of having lock files lying around if your process gets sent a SIGKILL
You can...
Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
...ve didn't work for -O2/-O3 (ld blew up with some crazy symbol redefinition error), so I don't believe the generated code is tuned for my microarchitecture.
There may be a way to do this slightly faster with SSE. I have no idea how, but with fast replication, packed bitwise AND, and swizzling instru...
What is the advantage of using REST instead of non-REST HTTP?
Apparently, REST is just a set of conventions about how to use HTTP . I wonder which advantage these conventions provide. Does anyone know?
...
Understanding what 'type' keyword does in Scala
...
Suppose you have the following scenario:
Here you will get compilation error, because eat method in classes Cow and Tiger do not override the eat method in class Animal, because their parameter types are different. It's Grass in class Cow, and Meat in class Tiger vs. Food in class Animal which i...
Why dict.get(key) instead of dict[key]?
...ever you choose it to be), whereas
dictionary["bogus"]
would raise a KeyError.
If omitted, default_value is None, such that
dictionary.get("bogus") # <-- No default specified -- defaults to None
returns None just like
dictionary.get("bogus", None)
would.
...
Is it correct to use alt tag for an anchor link?
...e that the src attribute isn’t allowed either.
By validating your HTML, errors like these are reported to you.
Note that the above is for HTML5, which is W3C’s HTML standard from 2014. In 2016, HTML 5.1 became the next HTML standard. Finding the allowed attributes works in the same way. You...