Re: An instructive example of trace-function and some example of debugging

[Icarus Sparry <usenet@icarus.freeuk.com>]

On Sat, 12 Jun 2010 10:43:46 -0700, bolega wrote:

> On Jun 10, 1:27 pm, bolega <gnuist...@gmail.com> wrote:
>> An instructive example of trace-function and some example of debugging,
>> for example, some of the error that pops up in lower window of emacs
>> and how to read/interpret it. Alternatively, a link to some page or
>> elisp manual but I am sure an expert here would have a superior
>> instruction as many replies here have shown.
>>
>> Thanks
>> Bolega
>>
>> trace-function is an interactive autoloaded Lisp function in `trace'.
>> [Arg list not available until function definition is loaded.]
>>
>> Traces FUNCTION with trace output going to BUFFER. For every call of
>> FUNCTION Lisp-style trace messages that display argument
>> and return values will be inserted into BUFFER. This function generates
>> the
>> trace advice for FUNCTION and activates it together with any other
>> advice
>> there might be!! The trace BUFFER will popup whenever FUNCTION is
>> called.
>> Do not use this to trace functions that switch buffers or do any other
>> display oriented stuff, use `trace-function-background' instead.
> 
> let me widen the newsgroups as there was no reply to this one in the
> first one.
> 
> Sometimes, in emacs, error takes places and the mode gets nested inside
> many brackets.
> 
> [(((.lisp...)))]
> 
> above line recalling from memory
> 
> what does it mean ? C-g does not get out of it.
> 
> What to do ?

If you are seeing [[[lisp]]] then you are in a "recursive edit".

This is not an error, it is a feature! The most common way to get into it 
is if you are doing a query-replace (M-% with standard bindings), and 
type control-r. This allows you to make some edits and then continue the 
query-replace.

The standard key binding to abort out of recursive edit is C-] (the [..] 
in the mode line is supposed to help you remember this key sequence).