[R] function doesn't exists but still runs.....

[Bill Dunlap]

Look into R's scoping rules.  E.g.,
https://bookdown.org/rdpeng/rprogdatascience/scoping-rules-of-r.html.

* When a function looks up a name, it looks it up in the environment in
which the function was defined.
* Functions in a package are generally defined in the package's environment
(although sometimes they are in a descendent of the parent's environment).
* When one searches an environment for a name, if it is not found in the
environment the search continues in the parent environment of that
environment, recursively until the parent environment is the empty
environment.

> with(environment(wdman::selenium), java_check)
function ()
{
    javapath <- Sys.which("java")
    if (identical(unname(javapath), "")) {
        stop("PATH to JAVA not found. Please check JAVA is installed.")
    }
    javapath
}
<bytecode: 0x000001fd0ab826a8>
<environment: namespace:wdman>

-Bill

On Thu, Jan 19, 2023 at 2:28 PM akshay kulkarni <akshay_e4 using hotmail.com>
wrote:

> dear members,
>                             I am using the RSelenium package which uses
> the function selenium() from the wdman package. The selenium function
> contains the function java_check at line 12. If I try to run it, it throws
> an error:
>
> >   javapath <- java_check()
> Error in java_check() : could not find function "java_check"
>
> Also:
>
> > exists("java_check")
> [1] FALSE
>
> But when I run selenium(), it works fine....
>
> How do you explain this conundrum? You can refer to this link:
> https://github.com/ropensci/wdman/issues/15
>
> Specifically what concept of R explains this weird behaviour?
>
> Thanking you,
> Yours sincerely,
> AKSHAY M KULKARNI
>
>
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>
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