Problem with ?Syntax

Gabor Grothendieck wrote:

I wasn't claiming there was an ambiguity but it does not perform
according to the operator precedence documented in ?Syntax .  If it
performed as documented it would give an error.
  

There are a few other errors in that page, e.g. saying that [ has 
greater priority than ::, but

version <- 1:10
base::version[1]

shows :: has higher priority.   I'll take a look.

Duncan Murdoch

On Sat, Feb 20, 2010 at 6:57 AM, Barry Rowlingson
<b.rowlingson at lancaster.ac.uk> wrote:
  

On Sat, Feb 20, 2010 at 9:52 AM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
    

In ?Syntax [ is given as higher priority than $ but BOD$demand[3]
seems to be the same as (BOD$demand)[3] contrary to [ being higher
priority.

      

BOD$demand[3]
        

[1] 19
      

(BOD$demand)[3]
        

[1] 19

What is the rule being used here?
      

 I think its the parser rule that defines the syntax of $ on a list. Does:

 BOD$(demand[3]) even work?

    

BOD$(demand[3])
      

Error: unexpected '(' in "BOD$("

 - no. The parser sees a $ and then gets the next token (gram.y shows
this to be a symbol or a string constant) as the thing to deal with.
Symbols  I can't think of an example where $ and [ could have
ambiguous precedence that is syntactically correct, so maybe the order
is irrelevant...

 Just for fun:

    

x=list(a=1,b=2)
x$"a[1]"=2
x$"a[1]"
      

[1] 2
    

x$a[1]
      

[1] 1


Barry