In a WarpIN installation script, any REXX code is called
before the script segment is interpreted. Any REXX calls
in the script will be replaced with the return value of the called
function or deleted from the script if no value is returned.
With WarpIN's REXX support, you can therefore dynamically alter the
contents of an installation script. If you are familiar with JavaScript:
this can simulate the functionality of the document.write()
method,
but this could also be used to execute any other REXX code.
To use WarpIN's REXX support, you need to do two things in your script:
- Define REXX functions, which optionally can return a string
which is meaningful in a WarpIN installation script.
REXX code is defined using
REXX
blocks.
- Invoke (call) the functions from the position where the dynamic string
should be inserted. This is done using the following syntax:
=("functionname [parameters]")
where functionname
must match the function name of an
existing REXX
element.
The parameters
are optional and can be parsed in the REXX
code using the standard REXX parse
function.
If any REXX
elements are found in the script, WarpIN will do the
following:
- While reading a script, WarpIN stores the REXX code sections internally
with the function name given in the
NAME
attribute of the
REXX
element.
- Invoke all REXX function calls found in the script. All REXX function
calls are replaced with the return values of the respective REXX function which
was called. If the REXX function returned nothing, the function call is simply
removed.
- The modified script is then parsed a second time.
In other words, you can think about the
=(...)
sections as variable parts of the script which are only filled in
just before the script code is being interpreted.