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NAME macros - description of macro facility
DESCRIPTION The following commands are associated
with the macro facility.
lsdef - List the names and sizes of all
macros.
def m s Define
or redefine m to have the definition s, where s is a string.
Assignment is made immediately.
rdef m s
Define or redefine m to have the definition s, where s is a
string. Assignment is made when the enclosing statement block is
executed.
undef m1 [m2
... ] Remove macro definitions.
prdef [m1 ... ] Print
all (or selected) macro definitions.
Within a macro, the symbols $1, $2,
... are replaced with the arguments with which the macro is
invoked. Also,
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$0 is replaced with the macro name,
$* is replaced with all the arguments,
$# is replaced with the number of arguments,
\$ is a literal $.
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A macro argument is a string of characters separated by
spaces. Use quotes to include more than one string in a single
argument. Use \" or \', in arguments
to pass literal quotes to the macro. You can continue supplying
arguments on subsequent lines by putting a backslash at the end
of the previous line.
When a macro is defined without arguments, only the macro
name is replaced with the definition.
When a macro is defined with arguments and is encountered by
the program, all characters on that line up to a ;,
a { or the end of the line are eaten up, whether or
not the macro uses them as arguments. When numbered arguments
are referred to in the macro definition, but are missing when the
macro is invoked, they are replaced with zeros. If
$* is used in the definition and there are no
arguments, no characters are substituted.
There is a limit to the length of a macro definition and to
the number of arguments allowed. You will be informed if you
exceed these limits. Each macro definition consumes
approximately 20 bytes of dynamic memory. The macro definitions
themselves are stored in a file.
BUGS AND CAVEATS Beware of unwanted side affects when
referencing the same argument more than once. For example,
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def test 'a = $1; b = 2 * $1'
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invoked as test i++, would be replaced with a
= i++; b = 2 * i++, with the result that i is
incremented twice, even though that action is not apparent to the
user. The previous definition also would cause problems if
invoked as test 2+3, as that would be replaced with
a = 2+3; b = 2 * 2+3. The latter
expression evaluates to 7, not 10, as might have been intended by
the user. Use of parenthesis to surround arguments used in
arithmetic expressions in macro definitions will avoid such
problems, as in b = 2 * ($1).
EXAMPLES
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Notice the double quotes convert the arguments into a single
string, as required by the syntax of the unix()
built-in command. When invoked with no arguments, the macro
evaluates to unix("").
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def ct ' {
local c
if ((c = $1) == 0) tcount(1)
else if (c < 0) mcount(-c)
else tcount(c)
waitcount; getcounts
print S[0], S[1], S[2]
} '
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Notice that the argument $1 is referred to only
once, by using the local variable c. When invoked
with no arguments, the first line evaluates to if ((c = 0)
== 0).
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def hscan '
hklscan $1 $2 K K L L $3 $4
'
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SEE ALSO
def
undef
lsdef
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Last Formatted Jan 24, 2012
Last Updated 05/19/10
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