[BioC] Empty RangedData with value columns?

[Robert Scharpf]

Hi, 

Would it be possible to have a column (value) in a RangedData object persist even if it has zero length? 

For example,

RangedData(IRanges(), id=character())

has 0 value columns, though I think it would be nice if the 'id' column could persist.  Afterall, it is permissable to have a DataFrame with values that are of zero length

values <- DataFrame(id=character())
colnames(values)

But, these values disappear in the RangedData constructor:

space <- Rle(factor())
values <- split(values, space)
colnames(values)

where the last line above returns NULL.

Thanks-

Rob

> sessionInfo()
R Under development (unstable) (2012-02-10 r58315)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.iso885915       LC_NUMERIC=C                  
 [3] LC_TIME=en_US.iso885915        LC_COLLATE=en_US.iso885915    
 [5] LC_MONETARY=en_US.iso885915    LC_MESSAGES=en_US.iso885915   
 [7] LC_PAPER=C                     LC_NAME=C                     
 [9] LC_ADDRESS=C                   LC_TELEPHONE=C                
[11] LC_MEASUREMENT=en_US.iso885915 LC_IDENTIFICATION=C           

attached base packages:
[1] stats     graphics  grDevices datasets  utils     methods   base     

other attached packages:
[1] IRanges_1.13.22     BiocGenerics_0.1.4  BiocInstaller_1.3.7

loaded via a namespace (and not attached):
[1] tools_2.15.0