VARDIM for RPGLE

Quick explanation.

VARDIM is to DIM what VARCHAR is to CHAR.

Background

Interfacing with RPG complex structures can be done, however the implementations are not homogeneous.

Examples.

• In IWS you need a pseudo variable suffixed by the array name

• For DATA-INTO and DATA-GEN you need to explicitly describe metadata information on what the prefix for the the occurrence counter is

• XML_INTO and XML-GEN has the same issues as DATA-INTO and DATA-GEN. You need to explicitly describe metadata information what the prefix for the occurrence counter is

• PCML does not have a datatype that describes the variable length of an array, but is separated into the array and the length.

• Interfacing from other ILE languages does not have direct control of either setting or getting the number of elements.

• 
  

The idea.

Basically VARDIM is exactly like a VARCHARin the sense that the variable has a predefined integer in front of the actual data, and is supposed to be a datatype of itself.

Example:

Dcl-s myArray varchar(5) vardim(3); 

The memory map for this will be like this:

XXXXYYYYdata1YYYYdata2

Where XXXX is the integer value of 2and YYYY is the integer value of 5

Dcl-s myArray2 varchar(5:4) vardim(3:4); 

The memory map for this will be like this:

XXXXXXXXYYYYYYYYdata1YYYYYYYYdata2

Where XXXXXXXX is the long integer value of 2 and YYYYYYYY is the long integer value of 5

The *AUTO and *VAR are aiming to do what VARDIM is, but will not occur as a separate datatype, that is the point of the Idea.

The current definition of arrays with *AUTO and *VAR is still in action, however the actual occurrence counter is stored in the beginning of the VARDIM itself.

You could also consider that VARDIM is a combination of *AUTO and *VAR and therefore is mutually exclusive.

Implications and benefits

• PCML need to support that new datatype, however it will not be ambiguous in the interpretations of its usage.

• IWS - need to support this, however it dont need to produce an extra pseudo variable for this. Also it will be able to expose an array as the root without any object mapper for JSON with extra config in the settings.

• DATA-INTO,DATA-GEN,XML-INTO, XML-GEN need to support this, but don't need to declare the counter prefix in the parser/generation meta options

• Consumers and exposers from other ILE languages can with no ambiguity interface with RPG to set or get the correct number of active elements in an array.

• Also IMHO - it is more consistent with the declaration of variables and structures in RPG.