gdb: Setting setter return a bool to tell if the value changed
GDB can notify observers when a parameter is changed.
To do that, do_set_command (in gdb/cli/cli-setshow.c) compares the new
value against the old one before updating it, and based on that notifies
observers. This looks like something like:
int valuechanged = 0;
switch (cmd->var.type ())
{
case var_integer:
{
LONGEST new_val = parse_and_eval_long (arg)
if (new_val != cmd->var.get<int> ())
{
cmd->var.get<int> (new_val);
value_changes = 1;
}
}
break;
case var_string:
{
std::string val = std::string (arg);
if (new_val != cmd->var.get<std::string> ())
{
cmd->var.get<std::string> (new_val);
value_changes = 1;
}
}
break;
case...
/* And so on for all possible var_types. */
}
This comparison is done for each possible var_type, which leads to
unnecessary code duplication.
In this patch I propose to move all those checks in one place within the
setting setter method. This limits the code duplication and simplifies
the do_set_command implementation.
This patch also changes slightly the way a value change is detected.
Instead of comparing the user provided value against the current value
of the setting, we compare the value of the setting before and after the
set operation. This is meant to handle edge cases where trying to set
an unrecognized value would be equivalent to a noop (the actual value
remains unchanged).
There should be no user visible change introduced by this commit.
Tested on x86_64 GNU/Linux.
[1] https://review.lttng.org/c/binutils-gdb/+/5831/41
Change-Id: If064b9cede3eb56275aacd2b286f74eceb1aed11
2 files changed
