REXX Tips & Tricks:Miscellaneous

This section contains some further useful information.

Using PMREXX

The syntax for PMREXX is:

 >>──PMREXX───┬────┬──┬─────────────┬─┬───────────┬─><
              ├─/Q─┤  └─rexxprogram─┘ └─parameter─┘
              └─/T─┘

Where:

/Q: Close PMREXX after the REXX program ends (no "The program has ended" message box)
/T: Start PMREXX in trace mode
rexxprogram: Name of the rexx program
parameter: Parameter for the REXX program

All parameters, except rexxprogram, are optional.

Using PMREXX with the parameter /Q is useful for simple programs which only need to show a PM messagebox (using RxMessageBox). For an example see Saving the Desktop (3.0)

(see Run a REXX program under a specific environment on how to force a program to run under PMREXX)

Please note that you cannot use OS/2 commands that change the environment in a REXX program running under PMREXX. You have to use a similar REXX function for that purpose (e.g. directory() instead of CD, VALUE() instead of SET, etc.).

Warning: The default address environment for a REXX program started via PMREXX in WARP 3 is PMREXX; the default environment in WARP 4 is CMD. Therefore, you cannot distinguish between the environments using ADDRESS() in WARP 4!

Note: see also PMPopup/2 if you only want to use simple dialog boxes in REXX programs.

The RXQUEUE filter

The purpose of the RXQUEUE filter is to copy the output of an OS/2 program into a REXX queue (The RXQUEUE filter is the external program RXQUEUE.EXE - not the built-in function RXQUEUE!) The syntax for RXQUEUE filter is:

>>──RXQUEUE──┬───────────┬──┬────────┬──────><
             └─queuename─┘  ├─/FIFO──┤
                            ├─/LIFO──┤
                            └─/CLEAR─┘

The RXQUEUE filter usually operates on the default queue named "SESSION". However, if an environment variable named "RXQUEUE" exists, the RXQUEUE value is used for the queue name.

Parameters

queuename: This is the name of the queue to use. The queue must already exist. The name of a queue can only contain the following characters: 'A'...'Z', '0'...'9', '.', '!', '?' and '_'. Lowercase letters are converted to uppercase letters.
/LIFO: Stacks items from STDIN last in, first out (LIFO) on a REXX queue.
/FIFO: Queues items from STDIN first in, first out (FIFO) on a REXX queue.
/CLEAR: Removes all lines from a REXX queue.

Note: Again, do not confuse the RXQUEUE filter with the RXQUEUE built-in function! Note further that you cannot use the RXQUEUE filter to write a REXX queue to STDOUT - you've to write a REXX program to do this task. (see Write the REXX Queue to STDOUT for an example).

ANSI ESC Sequences

"Compiling" REXX programs

Prevent REXX from creating a token image

Set the read-only attribute of REXX cmds for which the REXX interpreter should not create a token image (or copy them to a read-only disk or to a filesystem not supporting Extended Attributes).

"Undocumented" REXX functions

The following REXX functions to work with DBCS mixed Strings are only documented in the IBM: OS/2 2.0 Procedures Language/2 Reference Manual and in the Object-Oriented REXX online documentation:

DBADJUST
DBBRACKET
DBCENTER
DBLEFT
DBRIGHT
DBRLEFT
DBRRIGHT
DBTODBCS
DBTOSBCS
DBUNBRACKET
DBVALIDATE
DBWIDTH

Well, for the "normal" REXX programmer only two of these functions are interesting (The functions also work with SBCS strings):

Name       DBRLEFT( string, n {,option} ) 
Function   Delete n chars beginning with the first char 
Example    DBRLEFT( "ABCDEFG", 2 ) gives "CDEFG"
Note       The parameter option is only needed for DBCS strings)
           For SBCS strings you should not use this parameter.

Name       DBRRIGHT( string, n {,option} ) 
Function   Delete n chars beginning with the last char 
Example    DBRRIGHT( "ABCDEFG", 3 ) gives "ABCD"
Note       The parameter option is only needed for DBCS strings)
           For SBCS strings you should not use this parameter.