Re: [Rd] [<-.POSIXlt changes order of attributes (PR#9197)

From: Gregor Gorjanc <gregor.gorjanc_at_bfro.uni-lj.si>
Date: Sat 02 Sep 2006 - 20:02:10 GMT

Hello,

Prof Brian Ripley wrote:
> Please point us to the documentation that says attributes are ordered.
> E.g. R-lang.texi says
>
> All objects except @code{NULL} can have one or more attributes attached
> to them. Attributes are stored as a list where all elements are named.
>
> (although in fact they are stored in a pairlist).
>
> I know of tens of functions that change the order of attributes, and
> did look at teaching identical() that they are not ordered. But
> since they are stored as a pairlist, it would be quite expensive.

I agree that there is no need for attributes to be always in the same order as this is tedious to achieve as you noted above, but identical() seems to care about this.

> (Given that attributes seem to be growing in use, another internal storage
> mechanism is becoming more appropriate.)

Which internal storage mechanism are you talking about here?

> BTW, all.equal() does not assume attributes are ordered.

-- 
Lep pozdrav / With regards,
    Gregor Gorjanc

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