xscat(...)

## Return a BString object:
xscat(BString("abc"), BString("EF"))
xscat(BString("abc"), "EF")
xscat("abc", "EF")

## Return a BStringSet object:
xscat(BStringSet("abc"), "EF")

## Return a DNAStringSet object:
xscat(c("t", "a"), DNAString("N"))

## Arguments are recycled to the length of the longest argument:
res1a <- xscat("x", LETTERS, c("3", "44", "555")) 
res1b <- paste0("x", LETTERS, c("3", "44", "555"))
stopifnot(identical(as.character(res1a), as.character(res1b)))

## Concatenating big XStringSet objects:
library(drosophila2probe)
probes <- DNAStringSet(drosophila2probe)
mm <- complement(narrow(probes, start=13, end=13))
left <- narrow(probes, end=12)
right <- narrow(probes, start=14)
xscat(left, mm, right)

## Collapsing an XStringSet (or XStringViews) object with a small
## number of elements:
probes1000 <- as.list(probes[1:1000])
y1 <- do.call(xscat, probes1000)
y2 <- do.call(c, probes1000)  # slightly faster than the above
y1 == y2  # TRUE
## Note that this method won't be efficient when the number of
## elements to collapse is big (> 10000) so we need to provide a
## collapse() (or xscollapse()) function in Biostrings that will be
## efficient at doing this. Please request this on the Bioconductor
## mailing list (http://bioconductor.org/help/mailing-list/) if you
## need it.