[Rd] substitute(x$y)) corrupts 'y' component (PR#731)

[Peter Dalgaard BSA]

Thomas Lumley <thomas@biostat.washington.edu> writes:

>      z<-quote(x$y)
>      x<-list(y=1:3)
> and you want to produce
>      list(y=1:3)$y
> 
> Suggestions?

Double substitute and eval, but there's a hitch:

> eval(substitute(substitute(z,list(x=x)),list(z=z)))
structure(list(y = c(1, 2, 3)), .Names = "y")$y

which is hardly avoidable since

> dput(x)   
structure(list(y = c(1, 2, 3)), .Names = "y")

However, 

> x<-quote(list(y=1:3))
> eval(substitute(substitute(z,list(x=x)),list(z=z)))
list(y = 1:3)$y


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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