[bug-recutils] Auto generated fields

[Jose E. Marchesi]

Hi.

I just merged a branch providing support for auto-generated fields.
They are a way to for example implement auto-counters and timestamps.

A new directive is available for use in record descriptor: %auto.  It
accepts a list of fields separated by blanks, and determines that those
fields shall be auto-generated when new records are inserted in the
record set.

For example, consider:

/
| %rec: Item
| %type: Id int
| %auto: Id
| 
| Id: 1
| Description: this is item 1
\

If a new item is inserted using recins, and no explicit Id is specified:

 $ recins -t Item -f Description -v "another item" items.rec

The newly created record will contain a unique Id:

/
| %rec: Item
| %type: Id int
| %auto: Id
| 
| Id: 1
| Description: this is item 1
|
| Id: 2
| Description: another item
\

The auto-increment functionality works with fields of type 'int' and
'range'.

If %auto is used with fields of type 'date', the generated fields will
contain the current date of the system at record creation.  This is
useful to implement timestamps:

/
| %rec: Item
| %type: Id int
| %type: Date date
| %auto: Id Date
|
| Id: 1
| Date: Sun Jan 30 21:24:28 CET 2011
| Description: this is item 1
\

Note that the auto-generation of the fields will be performed only if no
explicit values are specified for those fields in the recins invocation.
Aditionally, the --no-auto command line argument of recins can be used
to inhibit the generation.

Enjoy!

-- 
Jose E. Marchesi    address@hidden
GNU Project         http://www.gnu.org