Is a string all blanks?

OneBlank <- " "
TwoBlanks <- "  "
ThreeBlanks <- "   "
NoBlanks <- "NoBlanks"
bvec <- c(OneBlank, TwoBlanks ,ThreeBlanks ,NoBlanks)
bvec <- c(OneBlank, TwoBlanks ,ThreeBlanks ,NoBlanks, "  A   ")
grepl("^ *$", bvec)

windows 7
R 2.12.1

Is there any easy way to determine if a sting contains nothing but blanks? I need to check a series of strings of various length.

OneBlank <- " "
TwoBlanks <- " ?"
ThreeBlanks <- " ? "
NoBlanks <- "NoBlanks"

What I want would be a function such as ALLBLANKS that would return the following
ALLBLANKS(OneBlank) would be true (or 1)
ALLBLANKS(TwoBlanks) would be true (or 1)
ALLBLANKS(ThreeBlanks) would be true (or 1)
ALLBLANKS(NoBlanks) would be false (or 0)

Thanks,
John

John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

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