[Bioc-devel] Pushing towards a better home for matrix generics

Hi Aaron,

The 4 matrix summarization generics currently defined in BiocGenerics
are defined as followed:

   setGeneric("rowSums", signature="x")
   setGeneric("colSums", signature="x")
   setGeneric("rowMeans", signature="x")
   setGeneric("colMeans", signature="x")

The only reason for having these definitions in BiocGenerics is to
restrict dispatch the first argument. This is cleaner than what we would
get with the implicit generics where dispatch is on all arguments (it
doesn't really make sense to dispatch on toggles like 'na.rm' or
'dims'). Sticking to simple dispatch when possible makes life easier for
the developer (especially in times of troubleshooting) and for the user
(methods are easier to discover and their man pages easier to access).

However, the 4 statements above create new generics that mask the
implicit generics defined in the Matrix package (Matrix doesn't contain
any setGeneric statements for these generics, only setMethod
statements). This is a very unsatisfying situation and it has hit me
repeatedly over the last couple of years.

We have basically 3 ways to go. From simpler to more complicated:

1) Give up on single dispatch for these generics. That is, we remove the
4 statements above from BiocGenerics. Then we use setMethod() in package
code like Matrix does.

2) Convince the Matrix folks to put the 4 statements above in Matrix.
Then any BioC package that needs to define methods for these generics
would just need to import them from the Matrix package. Maybe we could
even push this one step further by having BiocGenerics import and
re-export these generics. This would make them "available" in BioC as
soon as the BiocGenerics is loaded (and any package that needs to define
methods on them would just need to import them from BiocGenerics).

3) Put the 4 statements above in a MatrixGenerics package. Then convince
the Matrix folks to define methods on the generics defined in
MatrixGenerics. Very unlikely to happen!

IMO 2) is the best compromise. Want to give it a shot?

H.


On 1/27/19 13:45, Aaron Lun wrote:

This is a resurrection of some old threads:

https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_pipermail_bioc-2Ddevel_2017-2DNovember_012273.html&d=DwIDaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=O21AQgvbUp3XRwM4jf0WeZA2ePj9yT3fc2X5hOsKNJk&s=pcpUyjpkQe6U79lZ_n2SANNp6Zj_s6i1Sq2yZx2NSjw&e=

https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_Bioconductor_MatrixGenerics_issues&d=DwIDaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=O21AQgvbUp3XRwM4jf0WeZA2ePj9yT3fc2X5hOsKNJk&s=NrmcVnmvgkDp3p64J-izZU9VD5nFsFCWOTI-TsnzCpY&e=

For those who are unfamiliar with this, the basic issue is that various
Matrix and BiocGenerics functions mask each other. This is mildly
frustrating in interactive sessions:

library(Matrix)
library(DelayedArray)
x <- rsparsematrix(10, 10, 0.1)
colSums(x) # fails
Matrix::colSums(x) # okay

... but quite annoying during package development, requiring code like
this:

     if (is(x, "Matrix")) {
         z <- Matrix::colSums(x)
     } else {
         z <- colSums(x) # assuming DelayedArray does the masking.
     }

... which defeats the purpose of using S4 dispatch in the first place.

I have been encountering this issue with increasing frequency in my
packages, as a lot of my code base needs to be able to interface with
both Matrix and Bioconductor objects (e.g., DelayedMatrices) at the
same time. What needs to happen so that I can just write:

     z <- colSums(x)

... and everything will work for both Matrix and Bioconductor classes?
It seems that many of these function names are implicit generics
anyway, can BiocGenerics take advantage of that for the time being?

Best,

Aaron

--
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
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