Visara Master Console Center Scripting Guide - Manual (Page 22)

Chapter 2 Advanced Topics
Scripting Guide 22
Script Writing Guidelines
The following coding guidelines and style suggestions increase code
readability and ease maintenance:
Coding Guidelines
ƒ End all scripts with RETURN, so they can be easily called from other
scripts.
ƒ Always check return values.
ƒ Use SCANP whenever possible, not SCANB.
ƒ Avoid using GOTOs, except with functions such as SCANP.
ƒ If a section of code is repeated, make it a subroutine.
ƒ Initialize variables before use.
ƒ Plan the script to ensure there are paths for each possible condition,
and avoid “fall-through” situations. For example, if a RETURN is not
specified, control of the script may fall through to the next subroutine
by default, and not be processed correctly.
ƒ Use Manifest Constants (see page 42), not values. For example,
TRUE|FALSE is preferred to 0|1.
ƒ SWITCH-ENDSWITCH statements should always have a DEFAULT:
condition to handle unexpected values.
Style Suggestions
ƒ Keep subroutines as brief and as simple as possible. If a subroutine
exceeds 100 lines, consider breaking it into several subroutines.
ƒ Precede all scripts or subroutines with a description, including pre-
and post-conditions as well as exceptions and return codes that may
be passed.
ƒ Use variables in place of literals wherever possible.
ƒ Comment at each gosub call, stating the reason for each call if it is not
obvious.
ƒ Include a commented usage statement for each subroutine if it is not
obvious.
ƒ Do not comment obvious statements, for example, “%Continue
:=FALSE //don’t continue”.
ƒ Try to use the same case for variable names throughout a script.
ƒ Indent statements within control loops (IF-ENDIF, WHILE-
ENDWHILE...).
ƒ Put one space after each open parenthesis, and also after each comma.
This allows use of the Ctrl-Left Arrow and Ctrl-Right Arrow keys to
jump to the next word.