English version
Accueil     À propos     Téléchargement     Ressources     Contactez-nous    

Ce site est rarement mis à jour. Pour les informations les plus récentes, rendez-vous sur le nouveau site OCaml à l'adresse ocaml.org.

Browse thread
picking / marshaling to strings in ocaml-revision-stable way
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: 2008-05-31 (09:38)
From: Berke Durak <berke.durak@g...>
Subject: Re: [Caml-list] picking / marshaling to strings in ocaml-revision-stable way
I second Luca's suggestion to use Sexplib.  At the very least, use a
plaintext format.
Don't use Marshal for long-term storage of values.  Avoid it if you
can.  Been there, done that.

(1) Not type-safe.  Translation: your program *wil segfault* and you
won't know why.
(2) Not human-readable nor editable.
(3) Not future-proof.  What happens if you change your type
definition?  Your program
will segfault.  So you'll have to migrate your data.  But how?  You'll
have to find
the exact revision used to generate the binary data.  Good luck with
that.  Did you put
a revision number in your data?  Are you sure it was up-to-date?  Then
you'll have to hand-write a converter that uses type declarations from
the old and the new modules.
I hope your dependencies are not too complex.  Not fun *at all*.

However, there are some situations where Marshal is appropriate :

(1) Your data is not acyclic, contains closures, or needs sharing to
be compact enough.  Sexplib doesn't handle these.
(2) The data won't live long anyway.  As in: you're doing IPC between
known versions of Ocaml programs.
(3) You desperately need speed.  As in: you're processing 200GB of
Wikipedia data.
Then I can understand.
Berke Durak