Idiom #34 Create a set of objects

Declare and initialize a set x containing unique objects of type T.

Python

class T(object):
    pass

x = set(T())

Python

class T:
   ...

s = set(T() for _ in range(x))

Python

class T:
    def __init__(self, x):
        self.x = x
    def __hash__(self):
        return hash(self.x)
    def __eq__(self, t):
        return self.x == t.x
x = {T('abc'), T(123), T(lambda: ...)}

#include <unordered_set>

std::unordered_set<T, hasher, eq> x;

#include <unordered_set>

std::unordered_set<T> x;

using System.Collections.Generic;

HashSet<T> x = new HashSet<T>();

Demo
Doc

import std.container: redBlackTree;

auto x = redBlackTree!T;

var x = new Set<T>();

Demo

x := make(map[T]struct{})

Demo

x := make(map[T]bool)

Demo

import Data.Set

x = empty :: Set T

let x = new Set();

Demo
Doc

import java.util.Set;
import java.util.HashSet;

Set<T> x = new HashSet<T>();

import java.util.Set;
import java.util.HashSet;

Set<T> x = new HashSet<T>();
x.add(a);
x.add(b);

import static java.util.Set.of;
import java.util.Set;

Set<T> x = of(a, b, c);

use Moops;
use Set::Object qw();

class T {}
class Set::Object::T extends Set::Object {
    method BUILDARGS(T @items) { return {data => \@items}; }
    method insert(T @items) { $self->next::method(@items); }
}
my $x = Set::Object::T->new(T->new, T->new, T->new);