2 messages · Richard Cotton, Peter Dalgaard
If I want to use with inside a loop, it seems that next gets confused.
To reproduce:
for(lst in list(list(a = 1), list(a = 2), list(a = 3)))
{
with(lst, if(a == 2) next else print(a))
}
I expect 1 and 3 to be printed, but I see
[1] 1
Error in eval(expr, envir, enclos) :
no loop for break/next, jumping to top level
Is this
a) by design, or
b) a bug, or
c) a thing that is rare enough that I should just rewrite my code?
Regards, Richie Learning R 4dpiecharts.com
(a)/(c) mostly, I think. The crux is that "next" is unhappy about being evaluated in a different environment than the containing loop. Witness this:
for (i in 1:10) {if (i == 5) evalq(next); print(i)}
[1] 1 [1] 2 [1] 3 [1] 4 [1] 6 [1] 7 [1] 8 [1] 9 [1] 10
for (i in 1:10) {if (i == 5) evalq(next, new.env()); print(i)}
[1] 1 [1] 2 [1] 3 [1] 4 Error in eval(substitute(expr), envir, enclos) : no loop for break/next, jumping to top level
for (i in 1:10) {if (i == 5) evalq(next, parent.env(new.env())); print(i)}
[1] 1 [1] 2 [1] 3 [1] 4 [1] 6 [1] 7 [1] 8 [1] 9 [1] 10 -pd
On 27 Oct 2016, at 09:51 , Richard Cotton <richierocks at gmail.com> wrote:
If I want to use with inside a loop, it seems that next gets confused.
To reproduce:
for(lst in list(list(a = 1), list(a = 2), list(a = 3)))
{
with(lst, if(a == 2) next else print(a))
}
I expect 1 and 3 to be printed, but I see
[1] 1
Error in eval(expr, envir, enclos) :
no loop for break/next, jumping to top level
Is this
a) by design, or
b) a bug, or
c) a thing that is rare enough that I should just rewrite my code?
--
Regards,
Richie
Learning R
4dpiecharts.com
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