An ObjectSpace::WeakMap object holds references to any objects, but those objects can get garbage collected.

This class is mostly used internally by WeakRef, please use lib/weakref.rb for the public interface.

Methods
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Instance Public methods
[](p1)

Retrieves a weakly referenced object with the given key

Source: show 

static VALUE
wmap_aref(VALUE self, VALUE wmap)
{
    st_data_t data;
    VALUE obj;
    struct weakmap *w;
    rb_objspace_t *objspace = &rb_objspace;

    TypedData_Get_Struct(self, struct weakmap, &weakmap_type, w);
    if (!st_lookup(w->wmap2obj, (st_data_t)wmap, &data)) return Qnil;
    obj = (VALUE)data;
    if (!is_id_value(objspace, obj)) return Qnil;
    if (!is_live_object(objspace, obj)) return Qnil;
    return obj;
}
[]=(p1, p2)

Creates a weak reference from the given key to the given value

Source: show 

static VALUE
wmap_aset(VALUE self, VALUE wmap, VALUE orig)
{
    st_data_t data;
    VALUE rids;
    struct weakmap *w;

    TypedData_Get_Struct(self, struct weakmap, &weakmap_type, w);
    rb_define_final(orig, w->final);
    rb_define_final(wmap, w->final);
    if (st_lookup(w->obj2wmap, (st_data_t)orig, &data)) {
        rids = (VALUE)data;
    }
    else {
        rids = rb_ary_tmp_new(1);
        st_insert(w->obj2wmap, (st_data_t)orig, (st_data_t)rids);
    }
    rb_ary_push(rids, wmap);
    st_insert(w->wmap2obj, (st_data_t)wmap, (st_data_t)orig);
    return nonspecial_obj_id(orig);
}