Re: ncurses & commercial applications

[Dan Hatchen]

> <snip>

I wrote a 15,000 line program this spring using C, ncurses, and MySQL that 
tracks
and bills for
almost 300,000 items in a 3rd party warehouse. A smaller (1000 line) program
interfaces this
with their accounting program. I share this only to let you know that I have 
done
non-trivial
work with ncurses.

PS I prefer MySQL to Prostgres. Its faster and does so have transactions and row
locks, depending
on which table types you use.

#1 Look at the demo programs, they will give you a good start. The HOW-TOs are 
ok
but they
only tell you about the API, not how it fits together. I did quite a bit of 
source
tracing and printed
out some of the structures before I got a small working knowledge

I give some code examples here. I am sure that other have better ways of doing 
this,
but this is just
to illustrate

> While going through ncurses we have got the following problems :
>
> 1. How to validate date fields ?
>
> 2. How to create validation functions for each field where we can put our
> customised error messages for users ?
>
> 3. There is something called HOOKS. What is it ? We could not find any proper
> documentation regarding this in the HTML ncurse-intro by Raymond.

The 'HOOKS' are the answer to your first three questions. They are called when 
you
enter, leave a field
or a form. They are stored function pointers.

First write your 'handler'
-------------------------------------------------------------------------------------------------

void MyFormFieldInit( FORM * f )
{
    int x = field_index( current_field( f ) );     /* which field are we 
entering */

    switch( x )
    {
        case 1:        /* first field */
            /* do stuff */
        case 2:        /* second field */
            etc ...
    }
}
-------------------------------------------------------------------------------------------------

then , in your module entry point
-------------------------------------------------------------------------------------------------

void MyForm( void )
{
    void ( *fieldinit ) ( FORM * f1);        /* declare prototype */
    ...
    fieldinit = MyFormFieldInit;            /* set to your handler */
    ...
    /* build and instanciate MyForm as f */
    set_field_init( f, fieldinit );            /* ncurses call - registers the
function pointer*/
    /* need a message loop */
    do
    {
          switch ( form_driver( f, c = FormKeys( w ) ) )    /* FormKeys - my own
keystoke handler */

{                                                                               
 /*
I can override or pass to ncurses */
              case E_OK:
                  wrefresh( w );
                   break;

               case E_INVALID_FIELD:
                   MyFormFieldError( f );        /* I can display error messages
based on field I am in */
                   break;

               case E_UNKNOWN_COMMAND:
                    if ( !( finished = ( c == KEY_MAX ) ? TRUE : FALSE ) )
                    MyFormFunctions( f, c );        /* I can trap and respond 
to the
extended keys */
                   break;

               default:
                   beep( );
                   break;
            }
     }
     while ( !finished );
    ...
    /* free resources */
}

-------------------------------------------------------------------------------------------------



> 4. One of our requirement is Master - Detail forms say for entry of Invoices.
> There will be header part and than the detail part will contain 'n' no. of 
> items
> in the Invoice. Is there any easy way out for this ?
>

I did not find this part easy but through the use of panels was able to have
a header,
a scrolling window of line items,
a line item entry window,
and a footer.

Hope this helps some.

contact me private if you wish so we can keep this list clear

P.S

Thomas,

I have given some thought to a screen painter and a report writer like many 4GLs
have for
ncurses. I am short of time for a month or two, but do you think that there 
would be
enough demand
for a project like that ????

danh