Re: Starting out with sub-procedures

[Hans Boldt <boldt@xxxxxxxxxx>]

Booth Martin wrote:

> ok, I am learning.  slowly of course, but at least it is sinking in instead
> of bouncing off. 
>
>
>
> Here is the next question:
>
>
>
> Why does my new procedure that will run QCMDEXC need two parms in?  Why can
> t I just send the command and let the new procedure determine the command's
> length?

Because that's what QCMDEXC requires?

You could easily write a wrapper procedure that takes one CONST 
VARYING string parameter, that computes the length of that command 
and passes it on to QCMDEXC:

--------------------------------------------------------
P doCmd           b
D doCmd           pi
D   Command                   1000a   const varying
D QCmdExc         pr                  extpgm('QCMDEXC')
D                             1000a   const
D                               15p 5 const
 /free
    qcmdexc(Command:%len(Command));
 /end-free
P doCmd           e 

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

Thus demonstrating another advantage of procedures: Simplifying the 
calling of complex API's. In other words, converting the interface 
of some procedure into a different interface that's somehow better. 
In this case, the caller doesn't have to work out the length. Compare:

    doCmd ('CHGJOB DATFMT(' + fmt + ')');

with:

    cmd = 'CHGJOB DATFMT(' + fmt + ')';
    QCmdExc (cmd: %len(cmd));

Cheers! Hans