HP 3000 Manuals

System Debug Reference Manual

Variables 

System Debug provides variables in which values may be stored for use as
operands in expressions.  Variable names must begin with an alphabetic
character, which may be followed by any combination of alphanumeric,
apostrophe ('), underscore (_), or dollar sign ($) characters.  Variable
names are case insensitive and may not exceed 32 characters.

System Debug supports two levels of variable scoping:  global and local.
Global variables are defined by the VAR command and exist for the
lifetime of the System Debug session (unless removed by the VARD
command):

     $nmdebug > var v1 $2f 
     $nmdebug > var s2 = "hello mom" 
     $nmdebug > var p3:lptr = 2f.102c 

The type of a variable is determined by the type of the expression which
computes its value.  The optional :type syntax which follows the variable
name imposes a check on the expression type for that particular
assignment only.  It does not establish the variable's type over its
entire lifetime.  A value of a different type may be assigned to the same
variable by a subsequent VAR command.

Local variables are defined by the LOC command only from within macro
bodies and exist only for the lifetime of the macro in which they are
defined.  Local variable definitions nest with macro execution level, and
they supercede global variables of the same name.  Note that local
variables normally are not visible from outside the macro in which they
are created (that is, from macros called by the one in which they are
created).  To make local variable visible to called macros, the
environment variable NONLOCALVARS must be TRUE.

     loc v1 200
     loc s2 = "new string"

Note that, although a macro cannot reference the value of a global
variable once a local variable of the same name has been defined, it may
change the global value by using the VAR command instead of LOC.

!variable 

The use of the letters a through f to denote hex digits implies the
possibility of ambiguity between hex constants and variable names
composed of just these characters.  System Debug warns the user of this
occurrence when such variables are defined by the VAR and LOC commands,
but uses the value of the constant when the name occurs in an expression.
This may be overridden by preceding the variable name with the
exclamation point as follows:

     $nmdebug > var a 123 
     Variable name collides with hex numeric literal.  (warning #55)
       Name: "a"
     $nmdebug > wl a+1     /* a is a hex constant here
     $b
     $nmdebug > wl !a+1    /* !a references the variable a
     $124
     $nmdebug >

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