Path: utzoo!attcan!uunet!husc6!bloom-beacon!mit-eddie!uw-beaver!apollo!mrst!sdti!mjy
From: mjy@sdti.UUCP (Michael J. Young)
Newsgroups: comp.lang.c++
Subject: Disambiguating identifiers (was Re: ...Does C++ work with dbx...)
Keywords: C++, dbx, ctags
Message-ID: <269@sdti.UUCP>
Date: 19 May 88 21:13:00 GMT
References: <1158@daisy.UUCP> <7871@alice.UUCP>
Reply-To: mjy@sdti.UUCP (0000-Michael J. Young)
Distribution: na
Organization: Software Development Technologies, Sudbury MA
Lines: 42

In article <7871@alice.UUCP> shopiro@alice.UUCP writes:
>I regularly use dbx to debug C++ programs.  Setting breakpoints on line
>numbers works fine.  In order to set breakpoints on functions, or inspect
>the values of variables, you need to know the ``mangled'' version of
>the name you want to reference....

We've all had to deal with this problem in one way or another.  One of
the major advantages I see to native-code compilers is the debugging
support (i.e., access functions and variables by their unmangled identifiers)
that would come with it.  

>The next version of C++ will
>have a canonical ``demangler'' that can be incorporated into future
>debuggers.

I don't have access to a real C++ source-level debugger (such as the one
supplied with G++), but a colleague and I have been thinking about what it
takes for a person to be able to unambiguously specify identifiers for
setting breakpoints, inspecting variables, etc.

I suppose the C++ disambiguating operator (::) can be used for many
cases, but what about the following case:

overload foo;

int foo (int){...}
int foo (float){...}
int foo (int, int){...}

Now say that you want to set a breakpoint at the entry to the third function.
How would you tell a debugger which foo you are referring to without resorting
to line numbers?  The compiler disambiguates these on the basis of arguments
rather than scope.  How would a debugger do this?  

Using the output of cfront with a debugger such as dbx, one would simply (!)
refer to "_fooFII__" (or something equally obvious).  How would you do it
with the GNU debugger?
-- 
Mike Young - Software Development Technologies, Inc., Sudbury MA 01776
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"Bill & Opus in '88" -- Consider the alternatives!