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

[akshay kulkarni]

Dear Bill,
                Thanks for your reply...If I run selenium() in debug mode,  java_check() should work inside of selenium(), right?
Any other points to be considered when running selenium() in debug mode?

THanking you,
yours sincerely
AKSHAY M KULKARNI
________________________________
From: Bill Dunlap <williamwdunlap using gmail.com>
Sent: Friday, January 20, 2023 5:32 AM
To: akshay kulkarni <akshay_e4 using hotmail.com>
Cc: R help Mailing list <r-help using r-project.org>
Subject: Re: [R] function doesn't exists but still runs.....

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<mailto: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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