Stdlib.Oo(3)

hiii bestie 💖 welcome to the Stdlib.Oo(3) page, which lives in the OCaml library. This one is short and iconic, so let's get into it. ✨

🌸 NAME 🌸

Stdlib.Oo - no description 😭. That's literally what the manpage says, bestie. We move.

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🎀 Module 🎀

The module line is:

Module   Stdlib.Oo

That's the whole section. Slay. 💅

💖 Documentation 💖

Under documentation, it's the Oo module, wired up like this:

Module Oo
 : (module Stdlib__Oo)

🦋 copy 🦋

val copy : (< .. > as 'a) -> 'a

Oo.copy o returns a copy of object o — and by copy we mean a fresh object with the same methods and instance variables as o. No cap, it's giving duplicate-but-make-it-fresh. ✨

⚠️ Alert unsynchronized_access. Unsynchronized accesses to mutable objects are a programming error. This is a real warning, bestie — don't let unsynchronized access catch you slipping. 💀

🌈 id 🌈

val id : < .. > -> int

id returns an integer identifying this object, unique for the current execution of the program. The generic comparison and hashing functions are based on this integer. 👑

But here's the plot twist 😭: when an object is obtained by unmarshaling, the id is refreshed, and thus different from the original object. As a consequence, the internal invariants of data structures such as hash table or sets containing objects are broken after unmarshaling the data structures. That's a major "protect your invariants" moment, fr fr. 🫶

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mwah 💋 this page was brought to you by the footer energy: source/version OCamldoc, date 2026-06-22, and the page name Stdlib.Oo(3). periodt. 🎀