For catching runtime errors, Emacs offers similar integration with your symbolic debugger — that is, you can use an Emacs mode to set breakpoints in your programs and examine their runtime state. You run the debugger by sending it commands through an Emacs window. Whenever the debugger stops on a breakpoint, the message the debugger ships back about the source location is parsed and used to pop up a window on the source around the breakpoint.
Emacs's Grand Unified Debugger mode supports all the major C debuggers: gdb(1), sdb(1), dbx(1), and xdb(1). It also supports Perl symbolic debugging using the perldb module, and the standard debuggers for both Java and Python. Facilities built into Emacs Lisp itself support interactive debugging of Emacs Lisp code.
At time of writing (mid-2003) there is not yet support for Tcl debugging from within Emacs. The design of Tcl is such that it seems unlikely to be added.
