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Adding 'serial' to existing column in Postgres
...ok at the following commands (especially the commented block).
DROP TABLE foo;
DROP TABLE bar;
CREATE TABLE foo (a int, b text);
CREATE TABLE bar (a serial, b text);
INSERT INTO foo (a, b) SELECT i, 'foo ' || i::text FROM generate_series(1, 5) i;
INSERT INTO bar (b) SELECT 'bar ' || i::text FROM ...
Is it possible to override JavaScript's toString() function to provide meaningful output for debuggi
...You can override toString in Javascript as well. See example:
function Foo() {}
// toString override added to prototype of Foo class
Foo.prototype.toString = function() {
return "[object Foo]";
}
var f = new Foo();
console.log("" + f); // console displays [object Foo]
See this discussi...
How does the “final” keyword in Java work? (I can still modify an object.)
...
try to do t.foo = new ArrayList(); in the main method and you will get compilation error...the reference foo is binded to just one final object of ArrayList...it cannot point to any other ArrayList
– Code2Interface
...
How to test if list element exists?
...ome effort) contain NULL elements, it might not be enough to check is.null(foo$a). A more stringent test might be to check that the name is actually defined in the list:
foo <- list(a=42, b=NULL)
foo
is.null(foo[["a"]]) # FALSE
is.null(foo[["b"]]) # TRUE, but the element "exists"...
is.null(foo...
How to use sed to replace only the first occurrence in a file?
...
# sed script to change "foo" to "bar" only on the first occurrence
1{x;s/^/first/;x;}
1,/foo/{x;/first/s///;x;s/foo/bar/;}
#---end of script---
or, if you prefer: Editor's note: works with GNU sed only.
sed '0,/foo/s//bar/' file
Source
...
C++静态和多态，亦敌亦友 - C/C++ - 清泛网 - 专注C/C++及内核技术
...ostream>
using namespace std;
class Base
{
public:
virtual void foo(void){ cout << "Base::foo()" << endl; }
};
class Derived : public Base
{
public:
void foo(void){ cout << "Derived::foo()" << endl; }
} ;
class DerivedAgain : public Derived
{
public:
static void foo(...
How to get started with developing Internet Explorer extensions?
...rface(ClassInterfaceType.None)]
[Guid("D40C654D-7C51-4EB3-95B2-1E23905C2A2D")]
[ProgId("MyBHO.WordHighlighter")]
public class WordHighlighterBHO : IObjectWithSite, IOleCommandTarget
{
const string DefaultTextToHighlight = "browser";
IWebBrowser2 browser;
priv...
Difference between staticmethod and classmethod
...of example code will help: Notice the difference in the call signatures of foo, class_foo and static_foo:
class A(object):
def foo(self, x):
print "executing foo(%s, %s)" % (self, x)
@classmethod
def class_foo(cls, x):
print "executing class_foo(%s, %s)" % (cls, x)
...
Difference between 'struct' and 'typedef struct' in C++?
...entifiers (for typedef and other identifiers).
If you just said:
struct Foo { ... };
Foo x;
you would get a compiler error, because Foo is only defined in the tag namespace.
You'd have to declare it as:
struct Foo x;
Any time you want to refer to a Foo, you'd always have to call it a struc...
Converting a Java Keystore into PEM Format
... pretty straightforward, using jdk6 at least...
bash$ keytool -keystore foo.jks -genkeypair -alias foo \
-dname 'CN=foo.example.com,L=Melbourne,ST=Victoria,C=AU'
Enter keystore password:
Re-enter new password:
Enter key password for
(RETURN if same as keystore password):
bas...