RE: CALLB vs.CALLP

[Rob Berendt <rob@xxxxxxxxx>]

Good counterpoint.  I wanted to get the guy walking before he ran.




bvstone@taylorcorp.com on 03/31/2000 12:22:46 PM
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Subject:        RE: CALLB vs.CALLP

I never understood this example, and I've seen it from a lot of people.  If
you're making a subprocedure, prototype it so you only send the command.
Not the length.  You can define the length as %size(Command) in the
Subprocedure.

Then, you only need to do..

CALLP   #QcmdExc('CLRPFM FILE1')

Much easier.  And only 2 more seconds of setup.

Other times you will definatly want to do this when making wrappers for
APIs.  Sometimes they have a lot of parms you don't need to pass.  The
command length on QCMDEXC is one of them.

Brad

> -----Original Message-----
> From: Rob Berendt [mailto:rob@dekko.com]
> Sent: Friday, March 31, 2000 10:00 AM
> To: RPG400-L@midrange.com
> Subject: Re: CALLB vs.CALLP
> 
> 
> Prototyped calls take a little more setup.  However, they do give 
> you some advantages.  One is consistancy.  Two is the ability to do 
> calcs and stuff.
> 
> For example 
> << source member STDCOPY in QRPGLESRC in library MYCOPY >>
> D qcmdexc         PR                  EXTPGM('QCMDEXC')      
> D  cmd                       32702A   CONST OPTIONS(*VARSIZE)
> D  cmdlen                       15P 5 CONST                  
> << end of above source >>
> 
> The CONST will allow you to work with mismatched parameters 
> by automatically remapping them.
> For example
> << source member PGM in QRPGLESRC in library MYLIB >>
>  /COPY MYCOPY/QRPGLESRC,STDCOPY                               
>              
> D mycmd           C                   'OVRDBF INPUT 
> TOFILE(MYLIB/FTPSCRPT)'
> D CmdLen          S              3P 0 inz(35)                 
>              
> C                   callp     qcmdexc(mycmd:CmdLen)           
>              
>  * Notice that CmdLen is defined as 3,0 but it still works.
>  * We could skip the garbage of determining the size for CmdLen and 
>  * simply do the following:
> C                   callp     qcmdexc(mycmd:%len(%trim(mycmd)))
>  * Or even:
> C                   callp     qcmdexc('OVRDBF INPUT 
> TOFILE(MYLIB/FTPSCRPT)':
> C                                     %len(%trim('OVRDBF 
> INPUT TOFILE(MYLIB/FTPSCRPT)'
> C                                     )))
>  * We could also nest functions.  On this example I am leaving out
>  * the prototypes.
>  * DayOfW determines a numeric day of the week
>  * DayName takes this number and returns a name for this number.
> C                   eval      Text=DayName(DayOfW(datefield))
> 
> 
> 
> 
> 
> mwalter@netrax.net on 03/31/2000 10:40:42 AM
> Please respond to RPG400-L@midrange.com@Internet
> To:   rpg400-l@midrange.com@Internet
> cc:    
> Fax to:       
> Subject:      CALLB vs.CALLP
> 
> Is there an advantage of CALLP over CALLB when not returning a value?
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