[Bug]: `within` doesn't replace the lefthand side of an expression.

[llrs-roche]

What happened?

I wanted to mutate a variable by using as.factor but I found that using this approach doesn't replace the content but creates a new column:

library("teal.code")
var <- "Species"
q <- within(qenv(),
  {
    library("dplyr")
    iris <- iris
    iris2 <- mutate(iris, a = as.factor(a))
  },
  a = as.name(var)
)
setdiff(colnames(q$iris2), colnames(q$iris))
#> [1] "a"

^{Created on 2025-10-24 with reprex v2.1.1}

One workaround is to use the dplyr's walrus := assignment:

library("teal.code")
var <- "Species"
q <- within(qenv(),
  {
    library("dplyr")
    iris <- iris
    iris2 <- mutate(iris, a := as.factor(a))
  },
  a = as.name(var)
)
setdiff(colnames(q$iris2), colnames(q$iris))
#> character(0)

^{Created on 2025-10-24 with reprex v2.1.1}

but this might confuse readers of the code if this end up on the Show R code on teal.
If not a bug perhaps mentioning this on the documentation would be helpful to users.

Also, I realized that within doesn't have the @aliases within so users searching with ?within will not find it (but it is linked from eval_code and qenv).

sessionInfo()

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