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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...
Unique fields that allow nulls in Django
I have model Foo which has field bar. The bar field should be unique, but allow nulls in it, meaning I want to allow more than one record if bar field is null , but if it is not null the values must be unique.
...
Default value to a parameter while passing by reference in C++
...efault any argument you wish:
class A {};
class B {};
class C {};
void foo (A const &, B const &, C const &);
void foo (B const &, C const &); // A defaulted
void foo (A const &, C const &); // B defaulted
void foo (C const &); // A & B defaulted etc...
It i...
How to unit test an object with database queries
...jection pattern, as in the following pseudo-code:
class Bar
{
private FooDataProvider _dataProvider;
public instantiate(FooDataProvider dataProvider) {
_dataProvider = dataProvider;
}
public getAllFoos() {
// instead of calling Foo.GetAll() here, we are introducing...
What is the difference between join and merge in Pandas?
...ys use join on indices:
import pandas as pd
left = pd.DataFrame({'key': ['foo', 'bar'], 'val': [1, 2]}).set_index('key')
right = pd.DataFrame({'key': ['foo', 'bar'], 'val': [4, 5]}).set_index('key')
left.join(right, lsuffix='_l', rsuffix='_r')
val_l val_r
key
foo 1 4
ba...
TypeError: 'NoneType' object is not iterable in Python
...erable
Python methods return NoneType if they don't return a value:
def foo():
print("k")
a, b = foo() #TypeError: 'NoneType' object is not iterable
You need to check your looping constructs for NoneType like this:
a = None
print(a is None) #prints True
print(a is not No...
Concatenate two slices in Go
...}, []int{3,4}...)
This is just like any other variadic function.
func foo(is ...int) {
for i := 0; i < len(is); i++ {
fmt.Println(is[i])
}
}
func main() {
foo([]int{9,8,7,6,5}...)
}
share
...
What is Ruby's double-colon `::`?
What is this double-colon :: ? E.g. Foo::Bar .
10 Answers
10
...
Arguments or parameters? [duplicate]
...y functions as input, arguments are the things passed as parameters.
void foo(int bar) { ... }
foo(baz);
In this example, bar is a parameter for foo. baz is an argument passed to foo.
share
|
im...
Singleton pattern in nodejs - is it needed?
... are loaded. This means
(among other things) that every call to require('foo') will get
exactly the same object returned, if it would resolve to the same
file.
Multiple calls to require('foo') may not cause the module code to be
executed multiple times. This is an important feature. Wit...