select() does not preserve attributes for data frames

[stibu81]

According to the documentation, select() should preserve attributes ("Data frame attributes are preserved." in section Value). However, this seems to work only for tibbles, not for data frames. This is an reproducible example:

mtcars_df <- mtcars
attr(mtcars_df, "test") <- TRUE
mtcars_tib <- as_tibble(mtcars_df)
attr(mtcars_df, "test")
attr(mtcars_tib, "test")

attr(dplyr::select(mtcars_df), "test")
attr(dplyr::select(mtcars_tib), "test")

With dplyr 0.8.5, all the four calls of attr() return TRUE as expected. But with dplyr 1.0.0, attr(dplyr::select(mtcars_df), "test") returns NULL.

The result does not change, if some columns are selected.

[lionel-]

Right, currently the restoration when selecting columns is performed by [.tbl_df. Maybe we should call dplyr_reconstruct() in dplyr_col_select(), for consistency with other verbs.

[hadley]

Yeah, I think we should.

[hadley]

Minimal reprex:

library(dplyr, warn.conflicts = FALSE)

df1 <- structure(data.frame(x = 1), y = 2)
df2 <- structure(tibble(x = 1), y = 2)

attr(select(df1, x), "y")
#> NULL
attr(select(df2, x), "y")
#> [1] 2

^{Created on 2020-11-16 by the reprex package (v0.3.0.9001)}