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What does a lazy val do?
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In contrast to a method (defined with def) a lazy val is executed once and then never again. This can be useful when an operation takes long time to complete and when it is not sure if it is later used.
scala> class X { val x = { Thread.sleep(2000); 15 } }
defined class X
scala> class Y ...
How to reverse-i-search back and forth? [duplicate]
I use reverse-i-search often, and that's cool. Sometime though when pressing CTRL + r multiple times, I pass the command I am actually looking for. Because CTRL + r searches backward in history, from newest to oldest, I have to:
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What are the complexity guarantees of the standard containers?
Apparently ;-) the standard containers provide some form of guarantees.
3 Answers
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jQuery Determine if a matched class has a given id
...hat it won't apply to all #foo elements (though there should only be one), and it won't apply to all .bar elements (though there may be many). It will only reference elements that qualify on both attributes.
jQuery also has a great .is method that lets your determine whether an element has certain ...
XML Schema: Element with attributes containing only text?
...ed Dec 18 '08 at 2:18
David NormanDavid Norman
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Checking if an instance's class implements an interface?
... "yes";
}
You can use the "instanceof" operator. To use it, the left operand is a class instance and the right operand is an interface. It returns true if the object implements a particular interface.
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How do you use script variables in psql?
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Postgres variables are created through the \set command, for example ...
\set myvariable value
... and can then be substituted, for example, as ...
SELECT * FROM :myvariable.table1;
... or ...
SELECT * FROM table1 WHERE :myvariable IS NULL;
edit: As of psql 9.1, varia...
How do I rename a Git repository?
...s used by git clone master child, so we can simply rename it:
Open a command prompt (or file manager window).
Change to the directory that contains the repository directory (i.e., do not go into the repository directory itself).
Rename the directory (for example, using mv from the command line or...
How to lock orientation during runtime
...ing runtime? For example I'd like to allow the user to lock the screen to landscape if the user currently in landscape and toggle the menu option.
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UIButton title text color
...e text color or the shadow color. Instead, use the setTitleColor:forState: and setTitleShadowColor:forState: methods of this class to make those changes." No real explanation of the "why" though.
– clauswey
Mar 4 '15 at 12:12
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