Bug in s3_dispatch #28

Activity

1. hadley

   added

   bugan unexpected problem or unintended behavioran unexpected problem or unintended behavior

   on Oct 30, 2023
2. tslumley commented on Apr 9, 2024

   

   tslumley

   on Apr 9, 2024

   More actions

   I came here to report this
3. moodymudskipper commented on Feb 20, 2025

   

   moodymudskipper

   on Feb 20, 2025

   Last edited by moodymudskipper

   More actions

   s3_dispatch() names and looks up the methods naively without looking at the global tables, I think this would solve most issues, right now as soon as standard conventions are not followed it seams to break.

   here's another use case, rare but for one of the most used functions:

   s3 <- getNamespaceInfo("utils", "S3methods")
   s3[paste0(s3[,1], ".", s3[,2]) != s3[,3],]
   #>      [,1]   [,2]         [,3]         [,4]
   #> [1,] "head" "data.frame" "head.array" NA  
   #> [2,] "tail" "data.frame" "tail.array" NA  
   #> [3,] "tail" "table"      "tail.array" NA
   
   sloop::s3_dispatch(head(iris))
   #> => head.data.frame
   #>  * head.default

   And another example, not related to global tables here, but from the fact foo's name is used directly rather than finding the method in the body.

   foo <- function() {
     UseMethod("head")
   }
   sloop::s3_dispatch(foo(letters))
   #>    foo.character
   #> => foo.default

   This can be used, rather than converting the function symbol to character

   names(utils::isS3stdGeneric(foo))
   #> [1] "head"
   
4. yudalang3 commented on Apr 22, 2025

   

   yudalang3

   on Apr 22, 2025

   More actions

   I also very confused, What is the meanings of the => and *.
   For I do not find any document to see this #37 @hadley