Re: [RFC] add 'save-breakpoints' command

[Klee Dienes <klee@apple.com>]

> A related question is: maybe we should make all breakpoint commands 
> behave like this by default?

My opinion is that we should not.  I consider future-breakpoints as
something to be used only when GDB is for whatever reason unable to
properly load the symbols for something in advance.  In general, I
much-prefer the error-checking behavior of traditional 'break'.

> Can we perhaps come up with a better name instead of `future-break'?  It 
> doesn't really describe well enough what does this command do, IMHO.  For 
> example, if it is possible to put a breakpoint at the time the user 
> issues the command, GDB will do that without delays, so the word 
> ``future'' is inaccurate.

I'd certainly be open to new names, but after years of using
'future-break' and 'fb', it's hard for me to come up with one.  Other
options would be to use a variable such as 'set
defer-breakpoints-on-error 1' to enable the behavior (I tend to think
this is a bit cumbersome), or to add a '--retry' option to the
breakpoint commands.  Does anyone have any suggestions?

>> 	* main.c (captured_main): Initialize $input_radix and $output_radix.
>> 	These are referenced by a save-breakpoints file to preserve radix
>> 	across the breakpoint restoration.

> This aspect of save-breakpoints isn't mentioned in the gdb.texinfo 
> patch.  Please add it; I think it's important to say that in the manual, 
> since the radix has effect on features other than breakpoints.

In case I gave the wrong idea, the reason for the introduction of
these variables was to prevent the save-breakpoint implementation from
changing the default radix.  The idea is that the saved command file
contains commands of the form:

  set $current_radix = $input_radix
  set input-radix 012
  break internal_error
  set input-radix $current_radix

The only reason we need to add $input_radix as a variable is that
there is no good way to use the output of a command as input to
another command; otherwise we'd probably have done something like

  set $current_radix = `show input-radix`

.  I'm certainly willing to document the additional convenience
variables, but I'm not sure where a good section for them would be.
Perhaps in the documentation for 'set input-radix'?



Index: gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.59
diff -u -r1.59 gdb.texinfo
--- gdb.texinfo 2001/11/30 23:03:09     1.59
+++ gdb.texinfo 2001/12/11 16:22:23
@@ -2335,6 +2335,7 @@
 * Set Catchpoints::             Setting catchpoints
 * Delete Breaks::               Deleting breakpoints
 * Disabling::                   Disabling breakpoints
+* Saving::                      Saving breakpoints
 * Conditions::                  Break conditions
 * Break Commands::              Breakpoint command lists
 * Breakpoint Menus::            Breakpoint menus
@@ -2420,6 +2421,18 @@
 above (or no argument) specifying where to break.  @xref{Conditions,
 ,Break conditions}, for more information on breakpoint conditions.
 
+@kindex future-break
+@item future-break @var{args}
+Set a ``future'' breakpoint.  @var{args} are the same as for the
+@code{break} command and the breakpoint is set in the same way.
+However, if @value{GDBN} is unable to set the breakpoint when the
+command is executed, it will store the expression, and try again to set
+it after any new symbol files or shared libraries are loaded.  This
+command is typically used when setting breakpoints in shared libraries
+or plug-ins that are not able to be detected by GDB at start-up (either
+because they are dynamically loaded at run-time, or because GDB is for
+some other reason unable to detect them at start-up).
+
 @kindex tbreak
 @item tbreak @var{args}
 Set a breakpoint enabled only for one stop.  @var{args} are the
@@ -2942,6 +2955,22 @@
 breakpoints; see @ref{Continuing and Stepping, ,Continuing and
 stepping}.)
 
+@node Saving
+@subsection Saving breakpoints
+@cindex save breakpoints for future sessions
+
+Sometimes, it can be convenient to save the current set of breakpoints
+for use in a future debugging session:
+
+@table @code
+@kindex save-breakpoints
+@item save-breakpoints @var{filename}
+Save all current breakpoint definitions, together with their
+ignore-counts and command scripts, into the file @file{@var{filename}}.
+To read the saved breakpoint definitions, use the @code{source} command
+(@pxref{Command Files}).
+@end table
+
 @node Conditions
 @subsection Break conditions
 @cindex conditional breakpoints
@@ -13080,13 +13109,13 @@
 example, any of
 
 @smallexample
-set radix 012
-set radix 10.
-set radix 0xa
+set input-radix 012
+set input-radix 10.
+set input-radix 0xa
 @end smallexample
 
 @noindent
-sets the base to decimal.  On the other hand, @samp{set radix 10}
+sets the base to decimal.  On the other hand, @samp{set input-radix 10}
 leaves the radix unchanged no matter what it was.
 
 @kindex set output-radix
@@ -13103,6 +13132,10 @@
 @item show output-radix
 Display the current default base for numeric display.
 @end table
+
+The current input and output radixes can also be stored and set using
+the @value{GDBN} convenience variables @code{$input_radix} and
+@code{$output_radix}.
 
 @node Messages/Warnings
 @section Optional warnings and messages