R: Examples for 'base::exists'

### ** Examples

##  Define a substitute function if necessary:
if(!exists("some.fun", mode = "function"))
  some.fun <- function(x) { cat("some.fun(x)\n"); x }
search()

 [1] ".GlobalEnv"             "package:rediscc"        "package:sendmailR"     
 [4] "package:RCurl"          "package:httr"           "package:markdown"      
 [7] "package:knitr"          "package:png"            "package:Rserve"        
[10] "package:FastRWeb"       "package:Cairo"          "package:rcloud.support"
[13] "package:parallel"       "package:rjson"          "package:base64enc"     
[16] "package:stats"          "package:graphics"       "package:grDevices"     
[19] "package:utils"          "package:datasets"       "package:methods"       
[22] "Autoloads"              "package:base"

exists("ls", 2) # true even though ls is in pos = 3

[1] TRUE

exists("ls", 2, inherits = FALSE) # false

[1] FALSE

## These are true (in most circumstances):
identical(ls,   get0("ls"))

[1] TRUE

identical(NULL, get0(".foo.bar.")) # default ifnotfound = NULL (!)

[1] TRUE

## Don't show: 
stopifnot(identical(ls, get0("ls")),
          is.null(get0(".foo.bar.")))
## End(Don't show)

Examples for 'base::exists'

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