Using Alias for longer field names

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Update – December 17, 2014

Thanks to a PTF there is now a much easier way to use the ALIAS names in your RPG programs than the way described below.

Read Using aliases can be simple.

 

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The ALIAS keyword in DDS has been around for many, many years. I first used it in a programming environment where most of other the programmers used Cobol. They explained that if I added a ALIAS keyword to any files I created then they could use the longer alias name rather than the field name. I have to admit that the ability to use a field or variable name that was longer than six characters greatly appealed to me. This was the days of RPGIII and I had to deal with field names like J4UEEC for "End user currency", rather than the alias END-USER-CURRENCY that the Cobol programmers could use (you have to use the underscore in the alias name and the Cobol compiler translate it to a dash). The other thing I was jealous of the Cobol programmers was the Data division being the only place to define program variables.

Data Areas in the all free RPG

I have a couple of communications asking about how to "correctly" code a data structure to receive the data from and update a data area in the latest, all free, RPG. One of person even sent me their code, which I will be using for the basis for my examples.

While I am not sure if there is just one "correct" way to do this I will be giving my version of the following three scenarios:

1. Receive data from a data area into a data structure
2. Update the data area with data from a data structure
3. Equivalent of UDS

I am not going to describe the basics of how to code Data Structures in free format in this post, as I covered this in Defining variables in RPG all free.

Getting a list of files in IFS directory

Update

What I have described here has been made redundant by the introduction of the SQL Table Function IFS_OBJECT_STATISTICS.

Click on this link to read about IFS_OBJECT_STATISTICS.

 

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I needed to make a job that would display a list of files in an IFS directory, allow a user to select one, copy contents of the file in the IFS directory to a file in the IBM i, and process the data. Always hearing the mantra KISS, Keep It Simple Simon, in my mind I searched for alternatives.

The person who taught me this mantra always made last the 'S' interchangeable between 'Simon' and 'Stupid', which left me thinking if I was being stupid? She always refused to elaborate.

I could use the 'Display Object links' DSPLNK, command. Alas, the output from this either display or print. If I output to print I could then copy the spool file to a physical file, and… that is unnecessarily complicated for something that should be simple.

More about subprocedures

In my earlier post Subroutines versus Subprocedures I described some of the advantages of using subprocedures rather than subroutines. In it showed how you could use, what I call "open" subprocedures. An "open" subprocedure does not have a procedure interface specifications, therefore all of the variables defined in the main line/body are available in the subprocedures, and if you change the contents of one of those variables the changed value is seen in the main line/body.

The other type of subprocedure I call "closed". The subprocedure can be passed parameters and can return a single variable, which can be data structure with multiple subfields. A "closed" subprocedure is should be placed in a separate module, therefore, they are now available for multiple program to use. As the main line/body can only change the variables they pass to the subprocedure and the subprocedure can only return one pre-defined variable there is no accidentally changing to the values of the variables.

Many people commented on that post explaining the advantages of the "closed" subprocedure. I do agree and below I will describe how I code them and their advantages, including one potential gotcha.

Two user groups from France

I was recently browsing a French IBM i website when I found links to two User Groups in France:

• Le Club AS/400 Pays de Loire – www.clubas400pl.org
• Le Club Informatique de Bretagne – www.cibretagne.org

They share at forum at www.volubis.fr/forum/

I have added these links to this site's IBM i user groups page. You will find a link to the user groups page at the top of every page of this website.

Are there other user groups/clubs in France or anywhere else in the world? If you know of any not on the user groups page please use the Contact form to send me their details.