You can use the alias
and define commands
to create two types of macros:
An alias macro serves as a synonym
for one or more debugger commands. The debugger expands alias macros
only when the macro is at the beginning of a command line, or when
the macro follows a semicolon in a line of commands.
A define macro serves as a synonym for any string
of text, including debugger commands. The debugger always expands
a define macro no matter what position the macro occupies in a command
line.
For example, consider the following series of commands:
alias show print alias ali_X total
define def_X total
show ali_X
"ali_X" not found in current environment.
show def_X
total: 20 |
The alias
commands create show
as a synonym for the print
command, and ali_X
as a synonym for the variable total.
The define command
also creates a synonym for total,
but gives it the name def_X.
The debugger does not expand ali_X
in the command show ali_X
since ali_X does
not appear at the beginning of the line and it does not follow a
semicolon. However, the debugger does expand def_X
since define macros can appear anywhere on the command line. Also,
since the alias show
appears first in both of the last two command lines, the debugger
expands show
in both cases.
The debugger expands macros from left to right in the command
line. Upon finding a macro with arguments, the debugger inserts
the arguments into the macro definition. Then the debugger rescans
the command line, starting from where it found the macro.
You can define macros in terms of other macros and nest them.
Note that macros cannot be recursive.
Macro names may begin with a letter, a grave (`)
accent, a hyphen (-)
or an underscore (_).
Macros accept parameters and are defined like C language macros.
See the descriptions of the alias
and define commands
in the online command reference for syntax details.
You must delimit a macro name in a command string with characters
not allowed in a macro name, such as the space character. For example:
- define X len
Defines macro X
as len.
- print X
Expands to print len.
- print myX
Does not expand because the debugger does not treat
the letter y
as a delimiter.
Start a macro name with a grave accent (`)
to form a macro that can concatenate its text with other strings.
For example:
- define `X len
Defines macro `X
as len.
- print `X
Expands to print len.
- print my`X
Expands to print mylen.
Like arguments to debugger commands, macros are case-sensitive.
You can list alias macros using the list aliases
command; use list defines
to list define macros.
You can specify any string as the value for an actual parameter.
The debugger recognizes any string within matching brackets [],
braces `{}'', or parentheses ()
as a single argument. However, bracket pairs within the string are
treated in a special manner, and quotation marks are treated as
part of the string. The outermost brackets (within the parentheses
that delimit the argument) must balance; brackets, characters, and
punctuation marks within the outermost brackets are considered part
of the argument.
A period (.)
preceding a command string prevents the debugger from trying to
expand the string in an alias or define macro. For example, using
the period can prevent infinite looping in the following alias:
alias s[tep] .step -ignore |
Without the period, when the debugger encounters the step
command string, it would continue to apply the alias definition
indefinitely.
