Martin Maechler wrote:
(...)
> WK> which shows that raw won't coerce to the four first types in the
> WK> 'hierarchy' (excluding NULL), but it will to character, list, and
> WK> expression.
>
> WK> suggestion: improve the documentation, or adapt the implementation
> to
> WK> a more coherent design.
>
> Thank you, Wacek.
>
> I've decided to adapt the implementation
> such that all the above c(<raw> , <type>) calls' implicit
> coercions will work.
>
great!
>
> WK> (2)
> WK> incidentally, there's a bug somewhere there related to the condition
> WK> system and printing:
>
> WK> tryCatch(stop(), error=function(e) print(e))
> WK> # works just fine
>
> WK> tryCatch(stop(), error=function(e) sprintf('%s', e))
> WK> # *** caught segfault ***
> WK> # address (nil), cause 'memory not mapped'
>
> WK> # Traceback:
> WK> # 1: sprintf("%s", e)
> WK> # 2: value[[3]](cond)
> WK> # 3: tryCatchOne(expr, names, parentenv, handlers[[1]])
> WK> # 4: tryCatchList(expr, classes, parentenv, handlers)
> WK> # 5: tryCatch(stop(), error = function(e) sprintf("%s", e))
>
> WK> # Possible actions:
> WK> # 1: abort (with core dump, if enabled)
> WK> # 2: normal R exit
> WK> # 3: exit R without saving workspace
> WK> # 4: exit R saving workspace
> WK> # Selection:
>
> WK> interestingly, it is possible to stay in the session by typing ^C.
> the
> WK> session seems to work, but if the tryCatch above is tried once again,
> a
> WK> segfault causes r to crash immediately:
>
> WK> # ^C
> WK> tryCatch(stop(), error=function(e) sprintf('%s', e))
> WK> # [whoe...@wherever] $
>
> WK> however, this doesn't happen if some other code is evaluated first:
>
> WK> # ^C
> WK> x = 1:10^8
> WK> tryCatch(stop(), error=function(e) sprintf('%s', e))
> WK> # Error in sprintf("%s", e) : 'getEncChar' must be called on a CHARSXP
>
> WK> this can't be a feature. (tried in both 2.8.0 and r-devel; version
> WK> info at the bottom.)
>
> WK> suggestion: trace down and fix the bug.
>
> [not me, at least not now.]
>
sure; i might try to find the bug in spare time, but can't promise.
>
> WK> (3)
> WK> the error argument to tryCatch is used in two examples in ?tryCatch,
> but
> WK> it is not explained anywhere in the help page. one can guess that the
> WK> argument name corresponds to the class of conditions the handler will
> WK> handle, but it would be helpful to have this stated explicitly. the
> WK> help page simply says:
>
> WK> "
> WK> If a condition is signaled while evaluating 'expr' then
> WK> established handlers are checked, starting with the most recently
> WK> established ones, for one matching the class of the condition.
> WK> When several handlers are supplied in a single 'tryCatch' then the
> WK> first one is considered more recent than the second.
> WK> "
>
> WK> which is uninformative in this respect -- what does 'one matching the
> WK> class' mean?
>
> WK> suggestion: improve the documentation.
>
> Patches to tryCatch.Rd are gladly accepted
> and quite possibly applied to the sources without much changes.
>
ok, if you're willing to accept my suggestions i can try to suggest a
patch to the rd.
> Thanks in advance!
>
you're welcome.
best,
vQ
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