niche.param(x) requires `x$call[[2]]` to still be in the environment

[wlandau]

From @Rekyt via ropensci/drake#590:

library(ade4)
data(doubs)
dudi1 <- dudi.pca(doubs$env, scale = TRUE, scan = FALSE, nf = 3)
nic1 <- niche(dudi1, doubs$fish, scann = FALSE)
omi <- niche.param(nic1)
rm(dudi1)
omi <- niche.param(nic1)
#> Error in eval(expr, p): object 'dudi1' not found

If nic1 really needs dudi1 in order to use niche.param(), is there some way to make sure the value of dudi1 gets passed along with nic1? Maybe in a new list element of nic1 or another argument to niche.param()?

[sdray]

In ade4, many methods use this way to deal with previous analyses without storing objects. I know this is probably not the best way but it would require too much work to modify in all functions.