R devel - Apr 2005 - formals assignment now strips attributres

The assignment form of 'formals' strips attributes (or something close
to that) from the values in the list.  This wasn't intentional, was it?

The current behavior (2.0.0 through 2.1.0 on Windows at least):

 > fjj <- function() x
 > formals(fjj) <- list(x=c(a=2, b=4))
 > fjj
function (x = c(2, 4))
x


Previous behavior:

 > fjj <- function() x
 > formals(fjj) <- list(x=c(a=2, b=4))
 > fjj
function (x = structure(c(2, 4), .Names = c("a", "b")))
x

Patrick Burns

Burns Statistics
patrick@burns-stat.com
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")

Patrick Burns <pburns@pburns.seanet.com> writes:
> The assignment form of 'formals' strips attributes (or something
close
> to that) from the values in the list.  This wasn't intentional, was it?
> 
> The current behavior (2.0.0 through 2.1.0 on Windows at least):
> 
>  > fjj <- function() x
>  > formals(fjj) <- list(x=c(a=2, b=4))
>  > fjj
> function (x = c(2, 4))
> x
> 
> 
> Previous behavior:
> 
>  > fjj <- function() x
>  > formals(fjj) <- list(x=c(a=2, b=4))
>  > fjj
> function (x = structure(c(2, 4), .Names = c("a", "b")))
> x
It is only a buglet in deparsing:
>  formals(fjj)
$x
a b
2 4
> fjj()
a b
2 4
> as.list(fjj)
$x
a b
2 4

[[2]]
x

BTW, why is it that we cannot deparse named vectors
nicely?
> deparse(c(a=1,b=2))
[1] "structure(c(1, 2), .Names = c(\"a\",
\"b\"))"
> deparse(as.list(c(a=1,b=2)))
[1] "structure(list(a = 1, b = 2), .Names = c(\"a\",
\"b\"))"

Notice also that fjj constructed as above is not identical to 

function (x = c(a = 1, b = 2))
x

since the default expression is a vector in one case and  a call to
"c"
in the other. This is part of the problem; you're trying to deparse
something that cannot be the result of parsing. (The existence of such
objects is a generic problem in the R (and S) language).

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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