At startup, GDB overrides Guile’s
current-error-port to print using GDB’s output-paging streams.
A Guile program which outputs to one of these streams may have its
output interrupted by the user (see Screen Size). In this
situation, a Guile
signal exception is thrown with value
Guile’s history mechanism uses the same naming as GDB’s,
namely the user of dollar-variables (e.g., $1, $2, etc.).
The results of evaluations in Guile and in GDB are counted separately,
$1 in Guile is not the same value as
$1 in GDB.
GDB is not thread-safe. If your Guile program uses multiple threads, you must be careful to only call GDB-specific functions in the GDB thread.
Some care must be taken when writing Guile code to run in GDB. Two things are worth noting in particular:
SIGINT. Guile code must not override these, or even change the options using
sigaction. If your program changes the handling of these signals, GDB will most likely stop working correctly. Note that it is unfortunately common for GUI toolkits to install a
GDB introduces a new Guile module, named
methods and classes added by GDB are placed in this module.
GDB does not automatically
scripts must do this themselves. There are various options for how to
import a module, so GDB leaves the choice of how the
module is imported to the user.
To simplify interactive use, it is recommended to add one of the following
to your ~/.gdbinit.
guile (use-modules (gdb))
guile (use-modules ((gdb) #:renamer (symbol-prefix-proc 'gdb:)))
Which one to choose depends on your preference.
The second one adds
gdb: as a prefix to all module functions
The rest of this manual assumes the
gdb module has been imported
without any prefix. See the Guile documentation for
for more information
(see Using Guile Modules in GNU Guile Reference Manual).
(gdb) guile (value-type (make-value 1)) ERROR: Unbound variable: value-type Error while executing Scheme code. (gdb) guile (use-modules (gdb)) (gdb) guile (value-type (make-value 1)) int (gdb)
(gdb) module provides these basic Guile functions.
Evaluate command, a string, as a GDB CLI command. If a GDB exception happens while command runs, it is translated as described in Guile Exception Handling.
from-tty specifies whether GDB ought to consider this
command as having originated from the user invoking it interactively.
It must be a boolean value. If omitted, it defaults to
By default, any output produced by command is sent to
GDB’s standard output (and to the log output if logging is
turned on). If the to-string parameter is
#t, then output will be collected by
returned as a string. The default is
#f, in which case the
return value is unspecified. If to-string is
GDB virtual terminal will be temporarily set to unlimited width
and height, and its pagination will be disabled; see Screen Size.
Return a value from GDB’s value history (see Value History). The number argument indicates which history element to return.
If number is negative, then GDB will take its absolute value
and count backward from the last element (i.e., the most recent element) to
find the value to return. If number is zero, then GDB will
return the most recent element. If the element specified by number
doesn’t exist in the value history, a
gdb:error exception will be
If no exception is raised, the return value is always an instance of
<gdb:value> (see Values From Inferior In Guile).
Note: GDB’s value history is independent of Guile’s.
$1 in GDB’s value history contains the result of evaluating
an expression from GDB’s command line and
$1 from Guile’s
history contains the result of evaluating an expression from Guile’s
Append value, an instance of
<gdb:value>, to GDB’s
value history. Return its index in the history.
Putting into history values returned by Guile extensions will allow the user convenient access to those values via CLI history facilities.
Parse expression as an expression in the current language,
evaluate it, and return the result as a
The expression must be a string.
This function can be useful when implementing a new command
(see Commands In Guile), as it provides a way to parse the
command’s arguments as an expression.
It is also is useful when computing values.
For example, it is the only way to get the value of a
convenience variable (see Convenience Vars) as a