Re: Challenges using service programs, binding directories, etc.

On 8/18/2015 2:55 PM, Dan wrote:

...
What is the advantage of ...
d WrapText2 pr 12288 Varying RtnParm
d UnfText 8192 Varying Const Options(*VarSize)
d LineLen 5 0 Const
d LineBreak1 10 Varying Const Options(*NoPass)
d LineBreak2 10 Varying Const Options(*NoPass)
NotesArrayDS = WrapText2( %trimr( c_SPdetl) : 80 : '~' : '|' );
vs.
C call 'WRAPTEXT2'
C parm LongString 12288
C parm LineLength 5 0
C parm Tilde 1
C parm Vbar 1
C parm ReturnArray

You don't have to use CALL+PARM if you want to call a program.

I think a prototype with the EXTPGM keyword should be the second alternative, rather than CALL+PARM.

There are really two questions.

1. What are the advantages of using a prototyped call to a program vs CALL+PARM?

The main ones are a) the compiler will be able to detect some parameter mismatches at compile time; b) you can pass literals an expressions if you define the parameters with CONST; and c) you can't use CALL+PARM in free-form calculations.

2. What are the advantages of calling a procedure vs a program.

Here's one to add to those already given in this thread: If you can't return a value, callers have to define the "return parameter" with the exact size and type that the program expects. That might seem trivial, but it can get really annoying to have to define temporary variables just for making calls.

When I try to think of some advantages of calling a program over a procedure, I'm a bit hard-pressed.