Not an issue with pipes. The pipe just rewrites the expression to a
nested call and that is then evaluated. The call this produces is

quote(L |>
+    gsub(pattern = " ", replacement = "") |>
+    gsub(pattern = " ", replacement = "") |>
+    textConnection() |>
+    read.dcf())
read.dcf(textConnection(gsub(gsub(L, pattern = " ", replacement = ""),
    pattern = " ", replacement = "")))

If you run that expression, or just the argument to read.dcf, then you
get the error you report. So the issue is somewhere in textConnection().
This produces a similar message:

read.dcf(textConnection(c(L, "aaaaaaaaaaaaaaaaaa", "bbbbbbbbbbbbbbbb", 
"cccccccccccccccc", "ddddddddddddddddddd")))

File a bug report and someone who understands the textConnection()
internals better than I do can take a look.

Best,

luke

On Tue, 10 Aug 2021, Gabor Grothendieck wrote:

This gives an error bit if the first gsub line is commented out then there is no
error even though it is equivalent code.

 L <- c("Variable:id", "Length:112630     ")

 L |>
   gsub(pattern = " ", replacement = "") |>
   gsub(pattern = " ", replacement = "") |>
   textConnection() |>
   read.dcf()
 ## Error in textConnection(gsub(gsub(L, pattern = " ", replacement = ""),  :
 ##  argument 'object' must deparse to a single character string

That is this works:

 L |>
   # gsub(pattern = " ", replacement = "") |>
   gsub(pattern = " ", replacement = "") |>
   textConnection() |>
   read.dcf()
 ##      Variable Length
 ## [1,] "id"     "112630"

 R.version.string
 ## [1] "R version 4.1.0 RC (2021-05-16 r80303)"
 win.version()
 ## [1] "Windows 10 x64 (build 19042)"



--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
   Actuarial Science
241 Schaeffer Hall                  email:   luke-tier...@uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu

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