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What is the difference between a weak reference and an unowned reference?
...old on the referred object (a.k.a. they don't increase the retain count in order to prevent ARC from deallocating the referred object).
But why two keywords? This distinction has to do with the fact that Optional types are built-in the Swift language. Long story short about them: optional types offe...
Simple explanation of MapReduce?
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@lbolognini var total = orderes.Sum(o => o.UnitPrice * o.Quantity)
– chakrit
Apr 17 '09 at 21:35
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Using an integer as a key in an associative array in JavaScript
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yes, but when iterating they're not in any particular order (i.e. order is not guaranteed), which would be the point of numbering them, so it's a lot worse than just confusing.
– Julix
Jan 3 '17 at 5:43
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Git and Mercurial - Compare and Contrast
...age over shortened to 6-7 character revision identifiers, and imply strict ordering while revisions are only partially ordered (I mean here that revisions n and n+1 doesn't need to be parent and child).
Revision ranges
In Git revision ranges are topological. Commonly seen A..B syntax, which for lin...
Stack, Static, and Heap in C++
...not concern about that now. That's meant by the term static initialization order fiasco.
Dynamic storage duration
The last storage duration is dynamic. You use it if you want to have objects live on another isle, and you want to put pointers around that reference them. You also use them if your...
Select where count of one field is greater than one
... COUNT(Field1)
FROM Table1
GROUP BY Field1
HAVING COUNT(Field1) > 1
ORDER BY Field1 desc
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event.preventDefault() function not working in IE
... can use
event.returnValue = false;
to achieve the same result.
And in order not to get an error, you can test for the existence of preventDefault:
if(event.preventDefault) event.preventDefault();
You can combine the two with:
event.preventDefault ? event.preventDefault() : (event.returnValu...
javac is not recognized as an internal or external command, operable program or batch file [closed]
...of conflicts. (For instance, if you have JRE 8 and JDK 11 in PATH, in that order, then javac will invoke the Java 11 compiler, which will create version 55 .class files, but java will invoke the Java 8 JVM, which only supports up to version 52, and you will experience unsupported version errors and ...
Setting environment variables via launchd.conf no longer works in OS X Yosemite/El Capitan/macOS Sie
...environment file - just relaunch your application
Issues / problems:
In order your env variables were correctly taken by applications after system reboot you will need:
either login twice: login => logout => login
or close & re-open applications manually, where env variables should be...
What do we mean by Byte array? [closed]
...guous (side by side) bytes, such that it makes sense to talk about them in order: the first byte, the second byte etc..
Just as bytes can encode different types and ranges of data (numbers from 0 to 255, numbers from -128 to 127, single characters using ASCII e.g. 'a' or '%', CPU op-codes), each by...