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How can i tell if an object has a key value observer attached
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Put a try catch around your removeObserver call
@try{
[someObject removeObserver:someObserver forKeyPath:somePath];
}@catch(id anException){
//do nothing, obviously it wasn't attached because an exception was thrown
}
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What is the 'override' keyword in C++ used for? [duplicate]
... removed (not alternated). This is useful if the subclass is expecting a callback but it will never happen due to the library change, etc.
– Hei
Mar 11 '18 at 5:32
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How to find the Windows version from the PowerShell command line
...C
System Locale : ru;Russian
Hotfix(s) : 274 Hotfix(s) Installed.,[01]: KB2849697,[02]: KB2849697,[03]:...
Windows 10 output for the same command:
OS Name : Microsoft Windows 10 Enterprise N 2016 LTSB
OS Version : 10.0.14393 N/A Build 14393
OS Manufacturer ...
Best way to give a variable a default value (simulate Perl ||, ||= )
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In PHP 7 we finally have a way to do this elegantly. It is called the Null coalescing operator. You can use it like this:
$name = $_GET['name'] ?? 'john doe';
This is equivalent to
$name = isset($_GET['name']) ? $_GET['name']:'john doe'...
What does “abstract over” mean?
...the similarities. We say that we abstract over the differences, but this really means we're integrating by the similarities.
For example, consider a program that takes the sum of the numbers 1, 2, and 3:
val sumOfOneTwoThree = 1 + 2 + 3
This program is not very interesting, since it's not very a...
What JSON library to use in Scala? [closed]
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Lift-json is at version 2.6 and it works really well (and is also very well supported, the maintainer is always ready to fix any bugs users may find.
You can find examples using it on the github repository
The maintainer (Joni Freeman) is always reachable on the Lift...
How to validate an Email in PHP?
...hould be replaced by the preg family (PCRE Regex Functions). There are a small amount of differences, reading the Manual should suffice.
Update 1: As pointed out by @binaryLV:
PHP 5.3.3 and 5.2.14 had a bug related to
FILTER_VALIDATE_EMAIL, which resulted in segfault when validating
large ...
Docker: adding a file from a parent directory
...ce it tries to do it from its same directory (tbh, just what one would normally expect). Is there any way to do the same trick in Docker Hub?
– Marcel Hernandez
Mar 25 '16 at 20:31
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Number of processors/cores in command line
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Make sure to nproc --all for all installed Processing Units. Without --all, nproc only shows Processing Units available to the current process. Read the man page for more details. MMV.
– JamesThomasMoon1979
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How do you split a list into evenly sized chunks?
...t and empty the second list for the next round of data, but this is potentially extremely expensive.
64 Answers
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