大约有 40,000 项符合查询结果（耗时：0.0411秒） [XML]
instantiate a class from a variable in PHP?
...eck them out here (call_user_func_array , call_user_func).
example
class Foo {
static public function test() {
print "Hello world!\n";
}
}
call_user_func('Foo::test');//FOO is the class, test is the method both separated by ::
//or
call_user_func(array('Foo', 'test'));//alternatively you c...
Determine the type of an object?
...object, and isinstance() to check an object’s type against something. Usually, you want to use isistance() most of the times since it is very robust and also supports type inheritance.
To get the actual type of an object, you use the built-in type() function. Passing an object as the only param...
How to overload functions in javascript?
...by checking the type, presence or quantity of arguments.
jQuery does this all the time. You can make some of the arguments optional or you can branch in your function depending upon what arguments are passed to it.
In implementing these types of overloads, you have several different techniques yo...
Remove excess whitespace from within a string
I receive a string from a database query, then I remove all HTML tags, carriage returns and newlines before I put it in a CSV file. Only thing is, I can't find a way to remove the excess white space from between the strings.
...
What is the difference between Python's list methods append and extend?
...
Actually there's a big difference - x + [4, 5] gives you a new list assigned to x - x.extend() mutates the original list. I elaborate in my answer here below.
– Aaron Hall♦
Jul 17 '17 at 1...
How to update PATH variable permanently from Windows command line?
... do this can be found on MSDN. The key extract is this:
To programmatically add or modify system environment variables, add them to the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment registry key, then broadcast a WM_SETTINGCHANGE message with lParam set to the s...
New self vs. new static
...uated at compile time and must not depend on run-time information.
class Foo {
public $name = static::class;
}
$Foo = new Foo;
echo $Foo->name; // Fatal error
Using self::
class Foo {
public $name = self::class;
}
$Foo = new Foo;
echo $Foo->name; // Foo
Please note that ...
Adding 'serial' to existing column in Postgres
I have a small table (~30 rows) in my Postgres 9.0 database with an integer ID field (the primary key) which currently contains unique sequential integers starting at 1, but which was not created using the 'serial' keyword.
...
What is the difference between a definition and a declaration?
...// extern can be omitted for function declarations
class foo; // no extern allowed for type declarations
A definition actually instantiates/implements this identifier. It's what the linker needs in order to link references to those entities. These are definitions corresponding to the above declara...
Generate GUID in MySQL for existing Data?
...ch of data to a MySQL table and I have a column "GUID" that I want to basically fill down all existing rows with new and unique random GUID's.
...