Wacek Kusnierczyk wrote:
> interestingly,
>
> c(1, as.raw(1))
> # error: type 'raw' is unimplemented in 'RealAnswer'
>
>
three more comments.
(1)
the above is interesting in the light of what ?c says:
"
The output type is determined from the highest type of the
components in the hierarchy NULL < raw < logical < integer < real
< complex < character < list < expression.
"
which seems to suggest that raw components should be coerced to whatever
the highest type among all arguments to c, which clearly doesn't happen:
test = function(type)
c(as.raw(1), get(sprintf('as.%s',type))(1))
for (type in c('null', 'logical', 'integer', 'real', 'complex',
'character', 'list', 'expression'))
tryCatch(test(type), error = function(e) cat(sprintf("raw won't
coerce to %s type\n", type)))
which shows that raw won't coerce to the four first types in the
'hierarchy' (excluding NULL), but it will to character, list, and
expression.
suggestion: improve the documentation, or adapt the implementation to
a more coherent design.
(2)
incidentally, there's a bug somewhere there related to the condition
system and printing:
tryCatch(stop(), error=function(e) print(e))
# works just fine
tryCatch(stop(), error=function(e) sprintf('%s', e))
# *** caught segfault ***
# address (nil), cause 'memory not mapped'
# Traceback:
# 1: sprintf("%s", e)
# 2: value[[3]](cond)
# 3: tryCatchOne(expr, names, parentenv, handlers[[1]])
# 4: tryCatchList(expr, classes, parentenv, handlers)
# 5: tryCatch(stop(), error = function(e) sprintf("%s", e))
# Possible actions:
# 1: abort (with core dump, if enabled)
# 2: normal R exit
# 3: exit R without saving workspace
# 4: exit R saving workspace
# Selection:
interestingly, it is possible to stay in the session by typing ^C. the
session seems to work, but if the tryCatch above is tried once again, a
segfault causes r to crash immediately:
# ^C
tryCatch(stop(), error=function(e) sprintf('%s', e))
# [whoe...@wherever] $
however, this doesn't happen if some other code is evaluated first:
# ^C
x = 1:10^8
tryCatch(stop(), error=function(e) sprintf('%s', e))
# Error in sprintf("%s", e) : 'getEncChar' must be called on a CHARSXP
this can't be a feature. (tried in both 2.8.0 and r-devel; version
info at the bottom.)
suggestion: trace down and fix the bug.
(3)
the error argument to tryCatch is used in two examples in ?tryCatch, but
it is not explained anywhere in the help page. one can guess that the
argument name corresponds to the class of conditions the handler will
handle, but it would be helpful to have this stated explicitly. the
help page simply says:
"
If a condition is signaled while evaluating 'expr' then
established handlers are checked, starting with the most recently
established ones, for one matching the class of the condition.
When several handlers are supplied in a single 'tryCatch' then the
first one is considered more recent than the second.
"
which is uninformative in this respect -- what does 'one matching the
class' mean?
suggestion: improve the documentation.
vQ
> version
_
platform i686-pc-linux-gnu
arch i686
os linux-gnu
system i686, linux-gnu
status
major 2
minor 8.0
year 2008
month 10
day 20
svn rev 46754
language R
version.string R version 2.8.0 (2008-10-20)
> version
_
platform
i686-pc-linux-gnu
arch
i686
os
linux-gnu
system i686,
linux-gnu
status Under development
(unstable)
major
2
minor
9.0
year
2009
month
03
day
19
svn rev
48152
language
R
version.string R version 2.9.0 Under development (unstable) (2009-03-19
r48152)
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