diff options
Diffstat (limited to 'gdb/doc')
| -rw-r--r-- | gdb/doc/ChangeLog | 5 | ||||
| -rw-r--r-- | gdb/doc/gdb.texinfo | 63 |
2 files changed, 68 insertions, 0 deletions
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index 3e07eaa..e183332 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,3 +1,8 @@ +2013-09-16 Sergio Durigan Junior <sergiodj@redhat.com> + + * gdb.texinfo (Convenience Functions): Mention new convenience + function $_isvoid. + 2013-09-13 Andreas Arnez <arnez@linux.vnet.ibm.com> * gdb.texinfo (Decimal Floating Point format): Mention S/390. diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index a8c854e..65f63e4 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -9800,6 +9800,69 @@ function can be used in an expression just like an ordinary function; however, a convenience function is implemented internally to @value{GDBN}. +These functions do not require @value{GDBN} to be configured with +@code{Python} support, which means that they are always available. + +@table @code + +@item $_isvoid (@var{expr}) +@findex $_isvoid@r{, convenience function} +Return one if the expression @var{expr} is @code{void}. Otherwise it +returns zero. + +A @code{void} expression is an expression where the type of the result +is @code{void}. For example, you can examine a convenience variable +(see @ref{Convenience Vars,, Convenience Variables}) to check whether +it is @code{void}: + +@smallexample +(@value{GDBP}) print $_exitcode +$1 = void +(@value{GDBP}) print $_isvoid ($_exitcode) +$2 = 1 +(@value{GDBP}) run +Starting program: ./a.out +[Inferior 1 (process 29572) exited normally] +(@value{GDBP}) print $_exitcode +$3 = 0 +(@value{GDBP}) print $_isvoid ($_exitcode) +$4 = 0 +@end smallexample + +In the example above, we used @code{$_isvoid} to check whether +@code{$_exitcode} is @code{void} before and after the execution of the +program being debugged. Before the execution there is no exit code to +be examined, therefore @code{$_exitcode} is @code{void}. After the +execution the program being debugged returned zero, therefore +@code{$_exitcode} is zero, which means that it is not @code{void} +anymore. + +The @code{void} expression can also be a call of a function from the +program being debugged. For example, given the following function: + +@smallexample +void +foo (void) +@{ +@} +@end smallexample + +The result of calling it inside @value{GDBN} is @code{void}: + +@smallexample +(@value{GDBP}) print foo () +$1 = void +(@value{GDBP}) print $_isvoid (foo ()) +$2 = 1 +(@value{GDBP}) set $v = foo () +(@value{GDBP}) print $v +$3 = void +(@value{GDBP}) print $_isvoid ($v) +$4 = 1 +@end smallexample + +@end table + These functions require @value{GDBN} to be configured with @code{Python} support. |