conflicting note on global variable assignment about lintr HOT 8 CLOSED

Sorry for being unclear.
You should of course also define the global variable before writing to it.

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@krishnakeshav I recommend you read the R Packages section on internal state for packages to see how you should define and use global state in Packages.

Here is a MWE copied from there:

the <- new.env(parent = emptyenv())
the$favorite_letters <- letters[1:3]

#' Report my favorite letters
#' @export
mfl2 <- function() {
  the$favorite_letters
}

#' Change my favorite letters
#' @export
set_mfl2 <- function(l = letters[24:26]) {
  old <- the$favorite_letters
  the$favorite_letters <- l
  invisible(old)
}

For plain scripts, the error "cannot change value of locked binding ..." will disappear.

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is this part of a script or a package?

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@MichaelChirico

is this part of a script or a package?

Issue originally occurred in a package, but the above example is a script for the sake of reproducing.
The easiest way around this is to add return(g_var).

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Your code doesn't do what you think it does, and the warning is justified.

If you want to overwrite g_var in the outer scope from within the function, you need to use <<-.

from lintr.

Your code doesn't do what you think it does, and the warning is justified.

If you want to overwrite g_var in the outer scope from within the function, you need to use <<-.

using <<- in conjunction to glovalVariables also gives warning, see below -

It seems to me that <<- is not recognized as an operator to lint.

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Sorry for being unclear. You should of course also define the global variable before writing to it.

Thanks @AshesITR , it works well with scripts. In package, when I run lint active package from R studio, I don't get any notes. However, upon running R CMD check, I get the note as below -

no visible binding for '<<-' assignment to ‘result_index_list’

Note that, I have different code in case of R script in package.

result_index_list <<- NULL
some_fun <- function() {
  result_index_list <<- some_list_assignment
}

In above, if I use result_index_list <- NULL, then I get following runtime error -

Error in FUN(X[[i]], ...) :
cannot change value of locked binding for 'result_index_list'

I have R/globals.R with utils::globalVariables(c("result_index_list"))
Does lint behave differently in R CMD check than the scripts ?

from lintr.

@krishnakeshav I recommend you read the R Packages section on internal state for packages to see how you should define and use global state in Packages.

Here is a MWE copied from there:

the <- new.env(parent = emptyenv())
the$favorite_letters <- letters[1:3]

#' Report my favorite letters
#' @export
mfl2 <- function() {
  the$favorite_letters
}

#' Change my favorite letters
#' @export
set_mfl2 <- function(l = letters[24:26]) {
  old <- the$favorite_letters
  the$favorite_letters <- l
  invisible(old)
}

For plain scripts, the error "cannot change value of locked binding ..." will disappear.

This worked for me. Thanks again @AshesITR

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