read the currently open xlsx file

[JanMarvin]

I came across a feature request for this in openxlsx (ycphs/openxlsx#148 (comment)). While there might be an implementation in RDCOMClient I searched for a way to read the currently open xlsx file from the system process list. Maybe we can craft some optional wrapper function to make this a little bit simpler.
Writing to the file, will not be possible on Windows afaik, because the file is locked by the process that has opened it in the first place.

# open a file
xlsxFile <- system.file("extdata", "readTest.xlsx", package = "openxlsx2")
openXL(xlsxFile)

# get the path to the open file via the ps package
library(ps)
p <- ps()
# get the pid for the current program, in my case Excel on Mac
ppid <- p$pid[grepl("Excel", p$name)]
# get the list of open files for that program
pfiles <- ps_open_files(ps_handle(ppid))
pfile <- pfiles[grepl(".xlsx", pfiles$path),]

# read the written file, not the currently open file
sel <- grepl("^(.|[^~].*)\\.xlsx", basename(pfile$path))
path <- pfile$path[sel]

# read the currently open file
wb_to_df(path, colNames = F)