bug#24617: 26.0.50; Handlers in `condition-case' should have programmatic access to the backtrace

[Clément Pit--Claudel]

This sounds like a great idea!

As an aside, note that these things are not impossible; just tricky.  You just 
need to register your own debugger, then in that debugger function re-throw the 
error after recording the backtrace.  You also need to increment 
num-nonmacro-input-events from the debugger.

Clément.

On 2016-10-04 12:38, Philipp Stephani wrote:
> 
> Currently a handler in a `condition-case' form doesn't have access to
> the backtrace that was active when the signal was raised.  This makes
> many useful things impossible, such as re-raising signals or returning
> the backtrace to emacsclient.  I suggest either adding true exception
> objects (storing the error symbol, data, and backtrace), or at least
> providing a dynamic variable with the current backtrace.
> 
> 
> In GNU Emacs 26.0.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
>  of 2016-10-04 built on localhost
> Repository revision: e2913dc880b9843bf69cf885270551bafeb46120
> Windowing system distributor 'The X.Org Foundation', version 11.0.11501000
> System Description:   Ubuntu 14.04 LTS
> 
> Recent messages:
> For information about GNU Emacs and the GNU system, type C-h C-a.
> 
> Configured using:
>  'configure --with-modules --enable-checking
>  --enable-check-lisp-object-type'
> 
> Configured features:
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> TOOLKIT_SCROLL_BARS GTK3 X11 MODULES
> 
> Important settings:
>   value of $LANG: en_US.UTF-8
>   locale-coding-system: utf-8-unix
> 
> Major mode: Lisp Interaction
> 
> Minor modes in effect:
>   tooltip-mode: t
>   global-eldoc-mode: t
>   electric-indent-mode: t
>   mouse-wheel-mode: t
>   tool-bar-mode: t
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>   file-name-shadow-mode: t
>   global-font-lock-mode: t
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>   blink-cursor-mode: t
>   auto-composition-mode: t
>   auto-encryption-mode: t
>   auto-compression-mode: t
>   line-number-mode: t
>   transient-mark-mode: t
> 
> Load-path shadows:
> None found.
> 
> Features:
> (shadow sort mail-extr emacsbug message subr-x puny seq byte-opt gv
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> mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
> mail-utils time-date mule-util tooltip eldoc electric uniquify
> ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
> term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
> tabulated-list newcomment elisp-mode lisp-mode prog-mode register page
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> syntax facemenu font-core term/tty-colors frame cl-generic cham georgian
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> sha1 md5 base64 format env code-pages mule custom widget
> hashtable-print-readable backquote inotify dynamic-setting
> system-font-setting font-render-setting move-toolbar gtk x-toolkit x
> multi-tty make-network-process emacs)
> 
> Memory information:
> ((conses 16 97780 8564)
>  (symbols 48 20400 0)
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>

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