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.claude/skills/perl-io-async-future/SKILL.md  view on Meta::CPAN

        ->on_fail(sub {
            my $self = $weak or return;
            delete $self->{_reconnect_future};
            $self->_reconnect_attempt;        # try again
        });
}
```

**Rules:**
- Store the *whole chain* on the object (`$self->{_reconnect_future}`), not just the leaf.
- `weaken` `$self` inside callbacks — otherwise the chain holds the object alive forever.
- Always `delete $self->{_reconnect_future}` in both `on_done` and `on_fail`, or you'll guard out future reconnects with `return if $self->{_reconnect_future}`.
- On disconnect, **cancel the old `_connect_future`** so its async sub unwinds:
  ```perl
  if (my $f = delete $self->{_connect_future}) {
      $f->fail("disconnected: $reason") unless $f->is_ready;
  }
  ```

---

.claude/skills/perl-io-async-future/SKILL.md  view on Meta::CPAN

# Observe without composing (does NOT chain — return value ignored)
$f->on_done(sub { warn "done: @_" });
$f->on_fail(sub { warn "failed: $_[0]" });
```

**`then` vs `on_done`:**
- `then` returns a *new* Future; the callback returns a Future to chain. Use for control flow.
- `on_done` returns the *same* Future; callback return value is discarded. Use for side-effects/observation.

**Protective composition** (Future ≥ 0.51): pass extra siblings via `also =>` to keep them alive without making cancellation propagate:
```perl
Future->needs_all($f1, also => $f2, $f3);
```

---

## Pattern 5 — `->retain` for Fire-and-Forget

When you legitimately want to start an op and not wait, but still need it to *finish*: