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Re: RFC: gdb_test_multiple
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: Michael Elizabeth Chastain <mec at shout dot net>
- Cc: ac131313 at redhat dot com, gdb-patches at sources dot redhat dot com
- Date: Sun, 5 Jan 2003 12:38:48 -0500
- Subject: Re: RFC: gdb_test_multiple
- References: <200301051653.h05Grvd19105@duracef.shout.net>
On Sun, Jan 05, 2003 at 10:53:57AM -0600, Michael Elizabeth Chastain wrote:
> Hi Daniel,
>
> > This isn't a style thing, though. Let me point out the actual
> > syntactic difference between the two above: the strings are
> > expanded/substituted at the time of the call to gdb_test_multiple
> > instead of at the time of the actual expect {}, down the call chain.
>
> I don't understand. Are you saying that:
>
> set msg "breakpoint on Foo::Bar"
> gdb_test_multiple "break Foo::Bar" $msg {
> -re "foo" {
> ... fail $msg ...
> }
> }
>
> requires something gross in gdb_test_multiple in order to work?
No, but this similar construct:
set teststr "foo"
gdb_test_multiple "break Foo::Bar" $msg {
-re "$teststr" {
... fail $msg ...
}
}
does. And that idiom is all over the testsuite, for readability
purposes; see $hex, etc.
> I guess my question is: when does the "$msg" in "fail $msg" get
> expanded. If the caller expands it before calling gdb_test_multiple
> then I don't see the problem. If the caller passes "{ ... fail $msg ... }"
> without expanding $msg then I do see the problem.
{ } quoting in TCL completely disables expansion. Variables inside a
"proc name { args } { vars $here } are not expanded until the procedure
is called; similarly for the {} construct above.
If you think about it, this is logical. Consider
$expect_out(0,string), which is based on the regular expression match.
Its value isn't known when gdb_test_multiple is called, so it can't be
expanded until after the matching is done.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer