Tornado

Tornado 2.0
User’s Guide
7.6 Tcl: Debugger Automation
CrossWind exploits Tcl at two levels: like other Tornado tools, it uses Tcl to build
the graphical interface, but it also includes a Tcl interpreter at the GDB command
level. This section discusses using the Tcl interpreter inside the CrossWind
enhanced GDB, at the command level.
NOTE: For information about using Tcl to customize the CrossWind GUI, see
7.7 Tcl: CrossWind Customization, p.273. The discussion in this section is mainly of
interest when you need complex debugger macros; you might want to skip this
section on first reading.
Tcl has two major advantages over the other GDB macro facility (the define
command). First, Tcl provides control and looping (such as for, foreach, while, and
case). Second, Tcl procedures can take parameters. Tcl, building on the command
interface, extends the scripting facility of GDB to allow you to create new
commands.
7.6.1 Tcl: A Simple Debugger Example
To submit commands to the Tcl interpreter within GDB from the command panel,
use the tcl command. For example:
(gdb) tcl info tclversion
This command reports which version of Tcl is integrated with GDB. All the text
passed as arguments to the tcl command (in this example, info tclversion) is
provided to the Tcl interpreter exactly as typed. Convenience variables (described
in GDB User’s Guide: Convenience Variables) are not expanded by GDB. However, Tcl
scripts can force GDB to evaluate their arguments; see 7.6.3 Tcl: Invoking GDB
Facilities, p.268.
You can also define Tcl procedures from the GDB command line. The following
example procedure, mld, calls the load command for each file in a list:
(gdb) tcl proc mload args {foreach obj $args {gdb load $obj}}
You can run the new procedure from the GDB command line; for example:
(gdb) tcl mload vxColor.o priTst.o
To avoid typing tcl every time, use the tclproc command to assign a new GDB
command name to the Tcl procedure. For example:
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