Quoth Ben Escoto on Sweetmorn, the 56th of Chaos:
> I'm new to proto, but it seems like this is also a big drawback:
>
> > z <- 1
> > proto(baseenv(), expr={a=z})$a
> Error in eval(expr, envir, enclos) : object "z" not found
Ouch, good point; it may be that parent pollution is the lesser of two
evils, then.
It's a little bit of a catch 22, it seems; because even if you ascend
up the parent hierarchy until you hit a non-prototype, the first
environment that has `a' also has `z':
> library(proto)
> get.proto <- function(x, env) {
+ print(list(env=env,
+ ls=ls(env, all.names=TRUE)))
+ if (is.proto(env))
+ tryCatch(get(x, env=env, inherits=FALSE),
+ error=function(e) get.proto(x, env$.super))
+ else
+ stop(sprintf('object \'%s\' not found', x))
+
+ }
>
> (function() { z <- 1; get.proto('a', proto(eval={a=z})) })()
$env
<environment: 0x1d12180>
attr(,"class")
[1] "proto" "environment"
$ls
[1] ".super" ".that" "eval"
$env
<environment: 0x1d12918>
$ls
[1] "a" "z"
Error in get.proto(x, env$.super) : object 'a' not found
>
So, even if the $ environment diverged, say, from the eval
environment; the first relevant environment is already polluted.
It almost seems like you have to choose between eval and parent
pollution (unless I'm missing something).
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