getenv() can't differentiate "defined but empty" and "undefined"

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Subject: getenv() can't differentiate "defined but empty" and "undefined"
From: Martin Maechler (maechler@stat.math.ethz.ch)
Date: Wed 29 Sep 1999 - 23:57:09 EST


Message-Id: <199909291357.PAA15567@sophie.ethz.ch>

getenv(<varname>) currently returns ""
if the <varname> is undefined.

However, if <varname> is defined but empty,
getenv(<varname>) still only returns "".

I think this is quite unfortunate
but consistent with the prototype.

---
I'd propose to change the current behavior.
Something which should be pretty back compatible would 
for the first case (undefined environment variable)
to return "" with an attribute "defined" set to FALSE
i.e.  return(structure("", defined = FALSE))

Does anyone see a problem with this approach ?

Martin Maechler <maechler@stat.math.ethz.ch> http://stat.ethz.ch/~maechler/ Seminar fuer Statistik, ETH-Zentrum LEO D10 Leonhardstr. 27 ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND phone: x-41-1-632-3408 fax: ...-1228 <>< -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._


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