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What is an optional value in Swift?
...ng? = "Bertie"
Optionals (along with Generics) are one of the most difficult Swift concepts to understand. Because of how they are written and used, it's easy to get a wrong idea of what they are. Compare the optional above to creating a normal String:
var name: String = "Bertie" // No "?" after St...
How do servlets work? Instantiation, sessions, shared variables and multithreading
...'s web.xml and all of included web-fragment.xml files is parsed, and each <servlet>, <filter> and <listener> found (or each class annotated with @WebServlet, @WebFilter and @WebListener respectively) is instantiated once and kept in the server's memory as well. For each instantiate...
What are copy elision and return value optimization?
...e taken from Wikipedia:
struct C {
C() {}
C(const C&) { std::cout << "A copy was made.\n"; }
};
C f() {
return C();
}
int main() {
std::cout << "Hello World!\n";
C obj = f();
}
Depending on the compiler & settings, the following outputs are all valid:
Hello World!...
Why does @foo.setter in Python not work for me?
...>>> k.x
called getter
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/devel/class_test.py", line 6, in x
return self._x
AttributeError: 'testDec' object has no attribute '_x'
>>> k.x = 5
called setter
>>> k.x
called getter
...
Why are Standard iterator ranges [begin, end) instead of [begin, end]?
...e "natural" when sequences degenerate to empty ones, and also because the alternative (excluding the lower bound) would require the existence of a "one-before-the-beginning" sentinel value.
You still need to justify why you start counting at zero rather than one, but that wasn't part of your quest...
The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value
...ct with those modifications; that way, only changed fields are modified. Alternately, you can place hidden inputs in your page with the other fields populated, but that wouldn't be very friendly with concurrent edits.
Update:
Here's an untested sample of just updating some fields of your object (...
git revert back to certain commit [duplicate]
...
After 'git reset --hard <hash>' on your local, if you try to commit your latest changes to remote branch, you will most likely get an error indicating that 'Your branch is behind origin'. When that happens, you need to force the push using an f...
How do I increase the scrollback buffer in a running screen session?
...ode in a running session by typing Ctrl+A, :, then issuing the scrollback <num> command.
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Find when a file was deleted in Git
...
I was able to search using git log -- */<<filename>>.<<file extension>> not knowing the entire file path.
– Tom Howard
Sep 8 '15 at 16:38
...
Java switch statement: Constant expression required, but it IS constant
...brings another couple of different restrictions:
You must include a default case, even if you have case for every known value of the enum; see Why is default required for a switch on an enum?
The case labels must all be explicit enum values, not expressions that evaluate to enum values.
1 - Th...