🚀 go-pugleaf

John Leonard wrote:

>Just goes to show you if you want to code an IF statement code it in COBOL
>
>Those case macros just generate code that with generated labels creating
>code difficult to read modify and maintain.
>If see no advantage between an IF = instead  BE
>
>

There are *tremendous* advantages ...

So-called "label management" -- e.g., coming up with unique labels,
renumbering after an insertion of code (assuming you use numeric
suffixes as many people do), etc. -- is error prone busy work. Every
seasoned assembler programmer has seen the common error in which a loop
is created by "cloning" a routine from one part of a program to another
and forgetting to "fix up" one of the branches in the cloned routine.

HLASM is an equal opportunity assembler -- all labels are equal. The
assembler cannot distinguish a label that denotes the start of a
subroutine -- for which all source code references are legitimate --
versus those "utility labels" used to create programming structures such
as IF/THEN/ELSE, DO, SELECT, etc. Each label placed into the source code
provides an opportunity for someone to jump to it. Jumping to a label in
the middle of a "structure" is how unstructured "spaghetti" gets
created. The SPMs take away the opportunity to write unstructured code
by taking away the "utility labels" to which one might branch.

Indentation of code is _by far_ the most powerful heuristic ever devised
for programming languages to illustrate program flow. Some languages
(e.g., ISPF panel language, Python, etc.) *require* indentation whereas
most popular languages merely support its use. People write code
formatters to enforce standards by indenting code. Source code editors,
such as ISPF, have special support to help manage source code
indentation. Use of the SPMs facilitates the use of indentation for
assembler programs. For example:

|   *****************************************************
|   * Issue Warning Message for Each Unreferenced Group *
|   *****************************************************
|     ICM   R4,B1111,PSECGDEF       Point to group definitions
|     IF NZ                         If groups exist
|       DO INF                        Do for all groups
|         DOEXIT C,R4,GE,PSECGDEFP      Exit if no more groups
|         USING GRPDEF,R4           *** Synchronize GRPREF
|         LHI   R15,4                   Assume reference not found
|         ICM   R5,B1111,PSECGREF       Point to group references
|         IF NZ                         If references exist
|           USING GRPREF,R5           *** Synchronize GRPREF
|           DO INF                        Do for all references
|             DOEXIT C,R5,GE,PSECGREFP      Exit if no more references
|             IF CLC,GRPDEFName,EQ,         If matching group
|                 GRPREFName                (same)
|               XR    R15,R15                 Show reference found
|               LEAVE ,                       Exit the loop
|             ENDIF ,                       EndIf matching group
|             AHI   R5,GRPREFLen            Advance reference pointer
|           ENDDO ,                       EndDo for all references
|           DROP  R5                  *** Drop GRPREF
|         ENDIF ,                       EndIf references exist
|         IF LTR,R15,R15,NZ             If unreferenced group
|           .
|           . (issue warning message)
|           .
|         ENDIF ,                       EndIf unreferenced group
|         AHI   R4,GRPDEFLen            Advance group pointer
|       ENDDO ,                       EndDo for all groups
|     ENDIF ,                       EndIf groups exist

My hope is that one day HLASM will natively support -- as its name
implies -- a truly "high level" assembler language that will make the
SPMs unnecessary. In the mean-time, the SPMs provide an acceptable
substitute - IMHO.

--
.-----------------------------------------------------------------.
| Edward E. Jaffe                |                                |
| Mgr, Research & Development    | edjaffe@phoenixsoftware.com    |
| Phoenix Software International | Tel: (310) 338-0400 x318       |
| 5200 W Century Blvd, Suite 800 | Fax: (310) 338-0801            |
| Los Angeles, CA 90045          | http://www.phoenixsoftware.com |
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