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  • Perl

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).

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
}

Declaration of the variable and object instantiation/allocation for the attributes is combined into one statement for convenience. Separating this into three steps is also possible with attributes declared 'rw' (read-write).

Perl objects are reference counted. <http://p3rl.org/perlref#DESCRIPTION> When $v falls out of scope, its count is decreased to 0 and the dead object is garbage collected. <http://p3rl.org/Devel::Refcount> The memory it occupied is made available again for Perl to reuse.
#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}
    );
}

v.reset() is explicit deallocation, the object is also automatically deallocated when it goes out of scope.
New implementation...
< > ⌨
tkoenig 
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
}

#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.
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]
	};
}