binutils-gdb/gdb/cli/cli-setshow.h
Philippe Waroquiers 9ad9b77d64 Implement convenience functions to examine GDB settings.
The new convenience functions $_gdb_setting and $_gdb_setting_str
provide access to the GDB settings in user-defined commands.
Similarly, $_gdb_maint_setting and $_gdb_maint_setting_str
provide access to the GDB maintenance settings.

The patch was developed following a comment of Eli about the
'set may-call-functions'.  Eli said that user-defined functions
should have a way to change their behavior according to this setting.
Rather than have a specialized $_may_call_functions, this patch
implements a general way to access any GDB setting.

Compared to doing such access via Python 'gdb.parameter' and/or
'gdb.execute("set somesetting tosomevalue"):
* The 'with' command is much better than the above python usage:
  if the user types C-c or an error happens between the set pagination off
  and the python "set pagination on", the above python
  does not restore the original setting.

* Effectively, with the "gdb.parameter" python one liner, it is possible to do
  simple 'if' conditions, such as set and restore pagination.
  But mixing the "python if" within canned
  sequence of commands is cumbersome for non trivial combinations.
  E.g. if several commands have to be done for a certain condition
  accessed from python, I guess something like will be needed:
     python if __some_setting: gdb.execute("some command")
     python if __some_setting: gdb.execute("some other command")
     python if __some_setting: gdb.execute("some different command")
  (without speaking about nested "if-s").

  With the convenience function:
     if $_gdb_setting("some_setting")
        some command
        some other command
        some different command
     end
  Integer settings (for example print elements) will also be more difficult
  to use.
  For example, a user defined function that scans and prints a linked list
  might want to use the value of "set print elements" to stop printing
  the linked list.
  Doing that by mixing python expression/if is likely doable, but seems
  not easy with the above one liners.

So, in summary, the $_gdb_setting and $_gdb_setting_str avoids to have the
heterogeneous mix of python and GDB commands in one single script
(and of course, it works even if python is not configured, but that
must be an unusual setup I guess).

gdb/ChangeLog
2019-10-31  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* cli/cli-cmds.c (setting_cmd, value_from_setting)
	(gdb_setting_internal_fn, gdb_maint_setting_internal_fn)
	(str_value_from_setting, gdb_setting_str_internal_fn)
	(gdb_maint_setting_str_internal_fn): New functions.
	(_initialize_cli_cmds): Define the new convenience functions.
	* gdb/cli/cli-setshow.h (get_setshow_command_value_string): Constify.
	* gdb/cli/cli-setshow.c (get_setshow_command_value_string): Constify.
2019-10-31 23:31:43 +01:00

67 lines
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/* Header file for GDB CLI set and show commands implementation.
Copyright (C) 2000-2019 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef CLI_CLI_SETSHOW_H
#define CLI_CLI_SETSHOW_H
#include <string>
struct cmd_list_element;
/* Parse ARG, an option to a boolean variable.
Returns 1 for true, 0 for false, and -1 if invalid. */
extern int parse_cli_boolean_value (const char *arg);
/* Same as above, but work with a pointer to pointer. ARG is advanced
past a successfully parsed value. */
extern int parse_cli_boolean_value (const char **arg);
/* Parse ARG, an option to a var_uinteger or var_zuinteger variable.
Either returns the parsed value on success or throws an error. If
EXPRESSION is true, *ARG is parsed as an expression; otherwise, it
is parsed with get_ulongest. It's not possible to parse the
integer as an expression when there may be valid input after the
integer, such as when parsing command options. E.g., "print
-elements NUMBER -obj --". In such case, parsing as an expression
would parse "-obj --" as part of the expression as well. */
extern unsigned int parse_cli_var_uinteger (var_types var_type,
const char **arg,
bool expression);
/* Like parse_cli_var_uinteger, for var_zuinteger_unlimited. */
extern int parse_cli_var_zuinteger_unlimited (const char **arg,
bool expression);
/* Parse ARG, an option to a var_enum variable. ENUM is a
null-terminated array of possible values. Either returns the parsed
value on success or throws an error. ARG is advanced past the
parsed value. */
const char *parse_cli_var_enum (const char **args,
const char *const *enums);
extern void do_set_command (const char *arg, int from_tty,
struct cmd_list_element *c);
extern void do_show_command (const char *arg, int from_tty,
struct cmd_list_element *c);
/* Get a string version of C's current value. */
extern std::string get_setshow_command_value_string (const cmd_list_element *c);
extern void cmd_show_list (struct cmd_list_element *list, int from_tty,
const char *prefix);
#endif /* CLI_CLI_SETSHOW_H */