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Is the C# static constructor thread safe?
...stance will be synchronised. There are a variety of ways that this can be done; I've shown one below.
public class Singleton
{
private static Singleton instance;
// Added a static mutex for synchronising use of instance.
private static System.Threading.Mutex mutex;
private Singleton...
Is there a difference between foreach and map?
... some operation with side effects to each list member (such as saving each one to the database for example)
map iterates over a list, transforms each member of that list, and returns another list of the same size with the transformed members (such as converting a list of strings to uppercase)
...
Can enums be subclassed to add new elements?
... with numbers, with no automatic validation or anything. IMO enums are the one bit of Java which is actually better than C#.
– Jon Skeet
Nov 13 '10 at 13:21
21
...
Design Patterns: Factory vs Factory method vs Abstract Factory
...uit: Apple and Orange.
Factory
Factory is "fixed", in that you have just one implementation with no subclassing. In this case, you will have a class like this:
class FruitFactory {
public Apple makeApple() {
// Code for creating an Apple here.
}
public Orange makeOrange() {
// Cod...
Oracle SQL: Update a table with data from another table
...aulKarr's loop -- and if there is not a unique correlation, then more than one target row may be updated for each source row.
– Andrew Leach
Dec 17 '13 at 16:12
2
...
What are the differences between “=” and “
...vel (e.g.,
in the complete expression typed at the command prompt) or as one
of the subexpressions in a braced list of expressions.
Let’s not put too fine a point on it: the R documentation is (subtly) wrong [1]. This is easy to show: we just need to find a counter-example of the = operator ...
Argument list too long error for rm, cp, mv commands
...certain it will delete what you expect:
for f in *.pdf; do echo rm "$f"; done
And execute it:
for f in *.pdf; do rm "$f"; done
Also this is a portable approach as glob have strong and consistant behavior among shells (part of POSIX spec).
Note: As noted by several comments, this is indeed sl...
How to jump to a particular line in a huge text file?
...
linecache:
The linecache module allows one to get any line from a Python source file, while attempting to optimize internally, using a cache, the common case where many lines are read from a single file. This is used by the traceback module to retrieve source line...
Does Java have a HashMap with reverse lookup?
...ch class in the Java API. The Apache Commons class you want is going to be one of the implementations of BidiMap.
As a mathematician, I would call this kind of structure a bijection.
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improv...
python capitalize first letter only
...
Only because no one else has mentioned it:
>>> 'bob'.title()
'Bob'
>>> 'sandy'.title()
'Sandy'
>>> '1bob'.title()
'1Bob'
>>> '1sandy'.title()
'1Sandy'
However, this would also give
>>> '1bob s...