[Zope] One time persistent variable

[Jim Washington]

Antonio Beamud Montero wrote:

>Hi all:
>How I can make a variable from a Product persistent, but only exists a
>copy in the ZODB?, i.e. this variable is updated every 30 sec. and I
>don't want ZODB saves all old states of this variable, only the last...
>How I can make this...?
>
>Thanks in advance
>  
>
You do not specify whether it is a file-system Product or ZODB Product. 
 My preference would be to go simpler, rather than installing a 
non-replicating storage for something small like this.  That is, 
however, an option (search for non-replicating storage).

If it is a filesystem product, you have the option of writing the data 
to a file.  I would look at the FSCounter Product for an example of how 
this would be done.

If it is a ZODB product, use gadfly (you already have this!) or another 
SQL database if you are using one.  Create a database and table and 
Z[your Db] Adapter, if necessary, then 'get' and 'set' ZSQL Methods.

If it is a complicated variable, like a class instance, you might want 
to investigate the python "pickle" function.  This normally will only be 
available to a filesystem product or External Method.

You have many options.

-- Jim Washington