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You can implement new ROCGDB CLI commands in Guile. A CLI
command object is created with the make-command
Guile function,
and added to ROCGDB with the register-command!
Guile function.
This two-step approach is taken to separate out the side-effect of adding
the command to ROCGDB from make-command
.
There is no support for multi-line commands, that is commands that
consist of multiple lines and are terminated with end
.
The argument name is the name of the command. If name consists of multiple words, then the initial words are looked for as prefix commands. In this case, if one of the prefix commands does not exist, an exception is raised.
The result is the <gdb:command>
object representing the command.
The command is not usable until it has been registered with ROCGDB
with register-command!
.
The rest of the arguments are optional.
The argument invoke is a procedure of three arguments: self,
args and from-tty. The argument self is the
<gdb:command>
object representing the command.
The argument args is a string representing the arguments passed to
the command, after leading and trailing whitespace has been stripped.
The argument from-tty is a boolean flag and specifies whether the
command should consider itself to have been originated from the user
invoking it interactively. If this function throws an exception,
it is turned into a ROCGDB error
call.
Otherwise, the return value is ignored.
The argument command-class is one of the ‘COMMAND_’ constants
defined below. This argument tells ROCGDB how to categorize the
new command in the help system. The default is COMMAND_NONE
.
The argument completer is either #f
, one of the ‘COMPLETE_’
constants defined below, or a procedure, also defined below.
This argument tells ROCGDB how to perform completion
for this command. If not provided or if the value is #f
,
then no completion is performed on the command.
The argument prefix is a boolean flag indicating whether the new command is a prefix command; sub-commands of this command may be registered.
The argument doc-string is help text for the new command. If no documentation string is provided, the default value “This command is not documented.” is used.
Add command, a <gdb:command>
object, to ROCGDB’s
list of commands.
It is an error to register a command more than once.
The result is unspecified.
Return #t
if object is a <gdb:command>
object.
Otherwise return #f
.
By default, a ROCGDB command is repeated when the user enters a
blank line at the command prompt. A command can suppress this
behavior by invoking the dont-repeat
function. This is similar
to the user command dont-repeat
, see dont-repeat.
Convert a string to a list of strings split up according to ROCGDB’s argv parsing rules. It is recommended to use this for consistency. Arguments are separated by spaces and may be quoted. Example:
scheme@(guile-user)> (string->argv "1 2\\ \\\"3 '4 \"5' \"6 '7\"") $1 = ("1" "2 \"3" "4 \"5" "6 '7")
Throw a gdb:user-error
exception.
The argument message is the error message as a format string, like the
fmt argument to the format
Scheme function.
See Formatted Output in GNU Guile Reference Manual.
The argument args is a list of the optional arguments of message.
This is used when the command detects a user error of some kind, say a bad command argument.
(gdb) guile (use-modules (gdb)) (gdb) guile (register-command! (make-command "test-user-error" #:command-class COMMAND_OBSCURE #:invoke (lambda (self arg from-tty) (throw-user-error "Bad argument ~a" arg)))) end (gdb) test-user-error ugh ERROR: Bad argument ugh
If the completer option to make-command
is a procedure,
it takes three arguments: self which is the <gdb:command>
object, and text and word which are both strings.
The argument text holds the complete command line up to the cursor’s
location. The argument word holds the last word of the command line;
this is computed using a word-breaking heuristic.
All forms of completion are handled by this function, that is,
the TAB and M-? key bindings (see Command Completion),
and the complete
command (see complete).
This procedure can return several kinds of values:
<gdb:iterator>
object, it is iterated over to
obtain the completions. It is up to completer-procedure
to ensure
that the results actually do complete the word. Only
string elements of the result are used; other elements in the
sequence are ignored.
When a new command is registered, it will have been declared as a member of
some general class of commands. This is used to classify top-level
commands in the on-line help system; note that prefix commands are not
listed under their own category but rather that of their top-level
command. The available classifications are represented by constants
defined in the gdb
module:
COMMAND_NONE
¶The command does not belong to any particular class. A command in this category will not be displayed in any of the help categories. This is the default.
COMMAND_RUNNING
¶The command is related to running the inferior. For example,
start
, step
, and continue
are in this category.
Type help running at the ROCGDB prompt to see a list of
commands in this category.
COMMAND_DATA
¶The command is related to data or variables. For example,
call
, find
, and print
are in this category. Type
help data at the ROCGDB prompt to see a list of commands
in this category.
COMMAND_STACK
¶The command has to do with manipulation of the stack. For example,
backtrace
, frame
, and return
are in this
category. Type help stack at the ROCGDB prompt to see a
list of commands in this category.
COMMAND_FILES
¶This class is used for file-related commands. For example,
file
, list
and section
are in this category.
Type help files at the ROCGDB prompt to see a list of
commands in this category.
COMMAND_SUPPORT
¶This should be used for “support facilities”, generally meaning
things that are useful to the user when interacting with ROCGDB,
but not related to the state of the inferior. For example,
help
, make
, and shell
are in this category. Type
help support at the ROCGDB prompt to see a list of
commands in this category.
COMMAND_STATUS
¶The command is an ‘info’-related command, that is, related to the
state of ROCGDB itself. For example, info
, macro
,
and show
are in this category. Type help status at the
ROCGDB prompt to see a list of commands in this category.
COMMAND_BREAKPOINTS
¶The command has to do with breakpoints. For example, break
,
clear
, and delete
are in this category. Type help
breakpoints at the ROCGDB prompt to see a list of commands in
this category.
COMMAND_TRACEPOINTS
¶The command has to do with tracepoints. For example, trace
,
actions
, and tfind
are in this category. Type
help tracepoints at the ROCGDB prompt to see a list of
commands in this category.
COMMAND_USER
¶The command is a general purpose command for the user, and typically does not fit in one of the other categories. Type help user-defined at the ROCGDB prompt to see a list of commands in this category, as well as the list of gdb macros (see Canned Sequences of Commands).
COMMAND_OBSCURE
¶The command is only used in unusual circumstances, or is not of
general interest to users. For example, checkpoint
,
fork
, and stop
are in this category. Type help
obscure at the ROCGDB prompt to see a list of commands in this
category.
COMMAND_MAINTENANCE
¶The command is only useful to ROCGDB maintainers. The
maintenance
and flushregs
commands are in this category.
Type help internals at the ROCGDB prompt to see a list of
commands in this category.
A new command can use a predefined completion function, either by
specifying it via an argument at initialization, or by returning it
from the completer
procedure. These predefined completion
constants are all defined in the gdb
module:
COMPLETE_NONE
¶This constant means that no completion should be done.
COMPLETE_FILENAME
¶This constant means that filename completion should be performed.
COMPLETE_LOCATION
¶This constant means that location completion should be done. See Specifying a Location.
COMPLETE_COMMAND
¶This constant means that completion should examine ROCGDB command names.
COMPLETE_SYMBOL
¶This constant means that completion should be done using symbol names as the source.
COMPLETE_EXPRESSION
¶This constant means that completion should be done on expressions. Often this means completing on symbol names, but some language parsers also have support for completing on field names.
The following code snippet shows how a trivial CLI command can be implemented in Guile:
(gdb) guile (register-command! (make-command "hello-world" #:command-class COMMAND_USER #:doc "Greet the whole world." #:invoke (lambda (self args from-tty) (display "Hello, World!\n")))) end (gdb) hello-world Hello, World!
Next: Parameters In Guile, Previous: Writing a Guile Pretty-Printer, Up: Guile API [Contents][Index]