Developers of Sympa

[Guillaume Rousse <address@concealed>]

Le 24/05/2013 12:26, Marc Chantreux a écrit :
> Hello,
>
> The way i see things: Spool have 2 roles:
>
> * What to store (Message, ...)
> * How to store  (SQL, ...)
>
> so the way i would like to see things is:
>
> Sympa::Spool->new(qw[ for Messages by SQL ]);
>
> Will create a Spool for
>         Sympa::Spool::for::Messages
> backed end by
>         Sympa::Spool::by::SQL
>
> Sympa::Message::Spool->new will just honor the config
>
> Sympa::Message::Spool->new
>         ( by => [qw[ File serialize YAML root /tmp/sympa/spool ]] )
>
> Will create a Spool for
>         Sympa::Spool::for::Messages
> backed end by
>         Sympa::Spool::by::SQL
>
> so we can use roles to check that required are implemented
I prefer this class hierarchy, which clearly separates concerns.

However, what I realised in the mean time was than there is no evidence 
we need to have so many classes.

We do need to have distinct classes for backend type, sharing a common 
interface, so as to have an abstraction layer for calling code: the 
sympa daemon should be able to manage incoming message spool 
transparently, wether file-backed  or sql-backed.

However, is there any interest to have some abstraction over spool 
content (message, key, whatever) ? After all, the calling code usually 
know which is expected content over each spool...

So, if it's help making the code simpler, we could keep using only three 
classes:
Sympa::Spool
Sympa::Spool::File
Sympa::Spool::SQL

And have each of the two final classes implement distinct methods for 
storing distinct kind of content:
Sympa::Spool::File::add_message()
Sympa::Spool::File::add_key()
Sympa::Spool::File::add_something_else()

Sympa::Spool::SQL::add_message()
Sympa::Spool::SQL::add_key()
Sympa::Spool::SQL::add_something_else()

This doesn't prevent to have mixed-content spool by mistake, but code 
readability also helps to prevent coding errors :)
--
Guillaume Rousse
INRIA, Direction des systèmes d'information
Domaine de Voluceau
Rocquencourt - BP 105
78153 Le Chesnay
Tel: 01 39 63 58 31

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