Fwd: DBD::File updates and DBD::PO

Hi,

this morning the mail below arrives at my Inbox (in German).

I tried to answer at my best, but it feels very difficult to me to
explain some things clearer than I did in the documentation of
DBI::DBD::SqlEngine, DBD::File and DBD::File::Developers.

Than I've got an idea: the request for an example driver wasn't
well asked - Steffen doesn't need an example (we have a lot and
our documentation is good at all), Steffen needs a skeleton.

Probably it's not that what "we" want - but I think it's a good
feature request and it's reasonable for authors to ask for it.

In addition to DBI::DBD::Metadata, can we provide skeleton drivers
for:
1) DBD::File bases DBD's,
2) DBI::DBD::SqlEngine based DBD's, and/or
3) standalone DBD's (with or without XS)?

Writing the first and seconds shouldn't be a problem for me, but
I still have in mind what I first learned about writing a new DBD
from DBI::DBD: "The first rule for creating a new database driver
for the Perl DBI is very simple: DON'T!"

With the above skeletons, we could open a door to more DBD's.
I - speaking only for me - want that.

What do the others want?

Best regards,
Jens

-------- Original Message --------
Subject: here the english version
Date: Sun, 08 Aug 2010 19:13:27 +0200
From: Steffen Winkler <[email protected]>
To: Jens Rehsack <[email protected]>

Hi Jens!

Before I went to the YAPC I started to change my driver. And then I gave up.

At the time I created DBD::PO I started with DBD::CSV, a running software. 
Than I changed a lot and at the end was it DBD::PO. But I do not know 
exactly what I does. Now I want do create my driver more professional.

What I expect and where are the problems?

The first thing quickly becomes clear which packages I need.

Something is not always clear which global variables for which I must always 
provide.

Rather it was unclear what methods should I implement in which package and 
how the parameters are and what they return.

The documentation
  http://search.cpan.org/~timb/DBI-1.613_70/lib/DBD/File/Developers.pod
describes a lot methods verbally only. But I can not really read what is 
mandantory and what is optional. The verbal description alone is only 50% 
useful.

DBD::CSV or other special drivers are not really helpful as an example. An 
example needs more comments an expanations.

As an example, I would imagine that the database table could look like this:
  key1
  value1
  key2
  value2
The fields should be static:
  key
  value

The DBD::CSV is complex. It is a mix between a driver and format specials. 
It also supports both DBI interfaces. This reduces the readibility too.

An idea was to write such a minimal driver and place them at 
example/dbd_file/blabla.pm in the distribution. Than a writer of a new 
driver has a running example and can adapt this step by step.

Please tell me your opinion.

Greetings from Steffen.
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