大约有 12,000 项符合查询结果（耗时：0.0359秒） [XML]
What is “export default” in javascript?
...n you can import that default export by omitting the curly braces:
import foo from "foo";
foo(); // hello!
Update: As of June 2015, the module system is defined in §15.2 and the export syntax in particular is defined in §15.2.3 of the ECMAScript 2015 specification.
...
What is the difference between the GNU Makefile variable assignments =, ?=, := and +=?
...s evaluated when VARIABLE is accessed. It is equivalent to
ifeq ($(origin FOO), undefined)
FOO = bar
endif
See the documentation for more details.
Append
VARIABLE += value
Appending the supplied value to the existing value (or setting to that value if the variable didn't exist)
...
Set a default parameter value for a JavaScript function
...ing you want, including false or null. (typeof null == "object")
function foo(a, b) {
a = typeof a !== 'undefined' ? a : 42;
b = typeof b !== 'undefined' ? b : 'default_b';
...
}
share
|
imp...
Adding a Method to an Existing Object Instance
...here is a difference between functions and bound methods.
>>> def foo():
... print "foo"
...
>>> class A:
... def bar( self ):
... print "bar"
...
>>> a = A()
>>> foo
<function foo at 0x00A98D70>
>>> a.bar
<bound method A.bar of &...
Scala: What is a TypeTag and how do I use it?
... Scala's types are erased at runtime (type erasure). If we wanna do
class Foo
class Bar extends Foo
def meth[A](xs: List[A]) = xs match {
case _: List[String] => "list of strings"
case _: List[Foo] => "list of foos"
}
we will get warnings:
<console>:23: warning: non-variable typ...
Iterate over a list of files with spaces
...ld replace the word-based iteration with a line-based one:
find . -iname "foo*" | while read f
do
# ... loop body
done
share
|
improve this answer
|
follow
...
Create instance of generic type in Java?
...type information is available via reflection. e.g.,
public abstract class Foo<E> {
public E instance;
public Foo() throws Exception {
instance = ((Class)((ParameterizedType)this.getClass().
getGenericSuperclass()).getActualTypeArguments()[0]).newInstance();
...
}
}
...
Comma in C/C++ macro
...r as balanced pairs.) You can enclose the macro argument in parentheses:
FOO((std::map<int, int>), map_var);
The problem is then that the parameter remains parenthesized inside the macro expansion, which prevents it being read as a type in most contexts.
A nice trick to workaround this is...
std::enable_if to conditionally compile a member function
...;
std::is_same< T, int >::value >::type >
T foo() {
return 10;
}
*/
template < typename = typename std::enable_if< true >::type >
int foo();
/* instantiated from
template < typename = typenam...
Negative matching using grep (match lines that do not contain foo)
...t, the following may be what you're looking for grep "" /dev/null * | grep foo | grep -v bar | cut -d: -f1 | sort -u (why the first grep?, there's always a way :))
– Motti
Oct 25 '17 at 7:18
...