## Global env:

square <- function(x) {
  x ^ 2
}

const <- 2

nonassigned <- function(p) {
  t <- p * 2 # t assigned but not used
  p * 2
}

wronguse <- function(x) {
  return(square(...))
}

## Check global environment:

ls()
## [1] "const"       "nonassigned" "square"      "wronguse"

## findLocals
## ----------

codetools::findLocals(quote(q<-1))
## [1] "q"

codetools::findLocals({
  quote({
    square <- function(x) {
      x ^ 2
    }
    const <- 2
    })
  })
## [1] "const"  "square"

## checkUsage
## ----------

codetools::checkUsage(
  quote({
    square <- function(x) {
      x ^ 2
    }
  })
)
## <anonymous>: Error while checking: only works for closures

codetools::checkUsage(square)
## <anonymous>: Error while checking: object 'square' not found

## checkUsageEnv
## -------------

codetools::checkUsageEnv(globalenv())
## nonassigned: local variable 't' assigned but may not be used (<text>:8)
## wronguse: ... may be used in an incorrect context: 'square(...)' (<text>:13)

## collectUsage
## ------------

codetools::collectUsage(square)
## NULL

codetools::collectUsage(wronguse)
## Warning: <anonymous>: ... may be used in an incorrect context: 'square(...)' (<text>:13)
## NULL

## findGlobals
## -----------

codetools::findGlobals(square)
## [1] "{" "^"

codetools::findGlobals(nonassigned)
## [1] "{"  "*"  "<-"