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Allow t as a catch-all condition-case handler (Bug#24618)

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* src/eval.c (find_handler_clause): Accept a handler of t as always
matching.
(Fcondition_case):
* doc/lispref/control.texi (Handling Errors): Document this.
* etc/NEWS: Announce it.
This commit is contained in:
Noam Postavsky 2018-08-09 21:26:30 -04:00
parent 21637d5e5b
commit 425c281164
3 changed files with 13 additions and 7 deletions
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7
doc/lispref/control.texi
View file

@ -1878,9 +1878,10 @@ error occurs during @var{protected-form}.
Each of the @var{handlers} is a list of the form @code{(@var{conditions}
@var{body}@dots{})}. Here @var{conditions} is an error condition name
to be handled, or a list of condition names (which can include @code{debug}
to allow the debugger to run before the handler); @var{body} is one or more
Lisp expressions to be executed when this handler handles an error.
Here are examples of handlers:
to allow the debugger to run before the handler). A condition name of
@code{t} matches any condition. @var{body} is one or more Lisp
expressions to be executed when this handler handles an error. Here
are examples of handlers:
@example
@group

3
etc/NEWS
View file

@ -874,6 +874,9 @@ removed.
** lookup-key can take a list of keymaps as argument.
+++
** 'condition-case' now accepts 't' to match any error symbol.
+++
** New function 'proper-list-p'.
Given a proper list as argument, this predicate returns its length;

10
src/eval.c
View file

@ -1215,9 +1215,9 @@ Executes BODYFORM and returns its value if no error happens.
Each element of HANDLERS looks like (CONDITION-NAME BODY...)
where the BODY is made of Lisp expressions.
A handler is applicable to an error
if CONDITION-NAME is one of the error's condition names.
If an error happens, the first applicable handler is run.
A handler is applicable to an error if CONDITION-NAME is one of the
error's condition names. A CONDITION-NAME of t applies to any error
symbol. If an error happens, the first applicable handler is run.
The car of a handler may be a list of condition names instead of a
single condition name; then it handles all of them. If the special
@ -1854,7 +1854,9 @@ find_handler_clause (Lisp_Object handlers, Lisp_Object conditions)
for (h = handlers; CONSP (h); h = XCDR (h))
{
Lisp_Object handler = XCAR (h);
if (!NILP (Fmemq (handler, conditions)))
if (!NILP (Fmemq (handler, conditions))
/* t is also used as a catch-all by Lisp code. */
|| EQ (handler, Qt))
return handlers;
}