# Programming-Idioms

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# Idiom #209 Type with automatic deep deallocation

Declare a type t which contains a string s and an integer array n with variable size, and allocate a variable v of type t. Allocate v.s and v.n and set them to the values "Hello, world!" for s and [1,4,9,16,25], respectively. Deallocate v, automatically deallocating v.s and v.n (no memory leaks).

#include <string>
using namespace std::string_literals;
#include <vector>
#include <memory>

struct t {
std::string s;
std::vector<int> n;
};

auto v = std::make_unique<t>(
"Hello, world!"s,
decltype(t::n){1, 4, 9, 16, 25}
);
v.reset();

// Automatically:
void fn(){
auto v = std::make_unique<t>(
"Hello, world!"s,
decltype(t::n){1, 4, 9, 16, 25}
);
}
type t
character(len=:), allocatable :: c
integer, dimension(:), allocatable :: n
end type t
type(t), allocatable :: v

allocate (v)
v%s = 'Hello, world!'
v%n = [1,4,9,16,25]

deallocate (v)
type t struct {
s string
n []int
}

v := t{
s: "Hello, world!",
n: []int{1, 4, 9, 16, 25},
}
type
TDynIntArray = array of integer;
TT = record
s: string;
n: TDynIntArray;
end;
PTT = ^TT;

var
v: PTT;
begin
v := New(PTT);
v^.s := 'Hello world';
v^.n := TDynIntArray.Create(1,4,9,16,25);
Dispose(v);
end.
use Moops;
class T {
has 's', is => 'ro', isa => Str;
has 'n', is => 'ro', isa => ArrayRef[Int];
}

{
my \$v = T->new(s => 'Hello, world!', n => [1,4,9,16,25]);
# deallocation happens at closing brace, see explanation
}
class T:
def __init__(self, s, n):
self.s = s
self.n = n
return

v = T('hello world', [1, 4,  9, 16, 25])
del v
T = Struct.new(:s, :n)
v = T.new("Hello, world", [1, 4, 9, 16, 25])
v = nil
struct T {
s: String,
n: Vec<usize>,
}

fn main() {
let v = T {
s: "Hello, world!".into(),
n: vec![1,4,9,16,25]
};
}

tkoenig