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What exactly does an #if 0 … #endif block do?
...entire thing. And the #if 0s will nest with each other, like so:
#if 0
pre_foo();
#if 0
foo();
bar(x, y); /* x must not be NULL */
baz();
#endif
quux();
#endif
Although of course this can get a bit confusing and become a maintenance headache if not commented properly.
...
What does “abstract over” mean?
...mbers under a single symbol ns:
def sumOf(ns: List[Int]) = ns.foldLeft(0)(_ + _)
And we don't particularly care that it's a List either. List is a specific type constructor (takes a type and returns a type), but we can abstract over the type constructor by specifying which essential characteristi...
How to pass values between Fragments
...uper.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (findViewById(R.id.container) != null) {
if (savedInstanceState != null) {
return;
}
getFragmentManager().beginTransaction()
...
What should I name a table that maps two tables together? [closed]
...oducts and another category for recipe. for both tables we will have recipe_categories and product_categories, and since we can't just "categories" table name for both tables, in order to prevent the conflict, the junction tables for product and recipe will be "recipe_recipe_categories" and "product...
How do I check in JavaScript if a value exists at a certain array index?
...his answer: stackoverflow.com/a/39171620/3120446
– dx_over_dt
Jul 9 '19 at 20:19
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How to convert an array to object in PHP?
...son Medina pointed out, a really clean solution is to use the built-in json_ functions:
$object = json_decode(json_encode($array), FALSE);
This also (recursively) converts all of your sub arrays into objects, which you may or may not want. Unfortunately it has a 2-3x performance hit over the loop...
Convert string to integer type in Go?
...64); err == nil {
fmt.Printf("i=%d, type: %T\n", i, i)
}
var i int
if _, err := fmt.Sscan(s, &i); err == nil {
fmt.Printf("i=%d, type: %T\n", i, i)
}
Output (if called with argument "123"):
i=123, type: int
i=123, type: int64
i=123, type: int
Parsing Custom strings
There is also a...
Python nonlocal statement
...so that it looks more like the idioms of languages with closures.
def make_counter():
count = 0
def counter():
nonlocal count
count += 1
return count
return counter
Obviously, you could write this as a generator, like:
def counter_generator():
count = 0
...
What's the difference between eval, exec, and compile?
...n Python is whatever you can have as the value in a variable assignment:
a_variable = (anything you can put within these parentheses is an expression)
eval returns the value of the given expression, whereas exec ignores the return value from its code, and always returns None (in Python 2 it is a s...
How to create streams from string in Node.Js?
... to wrap the string in an array.
https://nodejs.org/api/stream.html#stream_stream_readable_from_iterable_options
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