Was internal routine called as Subroutine or Function?

Question

Was internal routine called as Subroutine or Function?

Swiftie (Programmer)

(OP)

14 Jan 17 07:39

Hello. I'm new around here.

Whilst I worked as a programmer (mainly in REXX) in IBM for 37 years, I'm now retired, but I hope that I'll qualify. I'll probably ask a few questions, and try to help most of the time.

I came here to ask a question, so here it is:

In the following snippet of code, using Open Object REXX, can the routine "Silent" determine if it has been called as a Subroutine or as a Function?

...
Call Silent
Say Silent(1)
...
Silent: Procedure
-- Was I called as a Subroutine or as a Function
...
Return 'Maybe'

Steve Swift http://www.swiftys.org.uk

mikrom (Programmer) · Answer 1 · 2017-01-14 15:15:55

The routine in ooRexx can be called as a subroutine (using CALL) or as a function.
In both cases the eventually arguments must be separated with commas, but when called as function they must be enclosed in (...) too.

When it is called as a subroutine (using CALL) then the eventually returned result is available in the special variable RESULT.

For example I tried this:

CODE

call silent
say result

call silent 1, 2
say result

say silent(3, 4)

exit

silent: procedure
  parse arg my_arg
  if my_arg = "" then
     rslt = "nothing passed"
  else
     rslt = "argument passed:" my_arg
  --
  return rslt

Result:

CODE

$ rexx foo_example.rex 
nothing passed
argument passed: 1
argument passed: 3

Swiftie (Programmer) · Answer 2 · 2017-01-14 16:36:36

Perhaps I should have asked:

Can the routine "Silent" determine whether it has been called as a Subroutine or called as a Function?

See http://www.swiftys.org.uk/wiz?568

A version which can tell the difference:

Call Silent
Say 'Silent was called as a' silent()
Exit

::Routine Silent
Parse source . how .
If How = 'SUBROUTINE' then say 'Silent was called as a' how
Return how

But, I frequently want to refer to variables from the calling routine, so ::REQUIRES is not always appropriate. Using Classic REXX, inside IBM, we had a CALLER MODULE which could be used to interrogate variables and environment in the calling code. But I don't recall that being able to determine HOW the called routine had been called. And I've never found an equivalent for OORexx

Steve Swift http://www.swiftys.org.uk

mikrom (Programmer) · Answer 3 · 2017-01-14 19:13:41

You answered your question self.
I didn't know it before and learned something new

But, it seems that

CODE

parse source operatingSystem commandType sourceFileName

contains in commandType FUNCTION or SUBROUTINE only when we use ooREXX specific declaration

CODE

::routine silent

When we use the standard REXX declaration

CODE

silent: procedure

then commandType contains in all cases COMMAND

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Was internal routine called as Subroutine or Function?