question

Gentlemen---these are all very clever workarounds, but please forgive me for
voicing my own opinion: IMHO, returning multiple values in a statistical
language should really be part of the language itself. there should be a
standard syntax of some sort, whatever it may be, that everyone should be
able to use and which easily transfers from one local computer to another.
It should not rely on clever hacks in the .Rprofile that are different from
user to user, and which leave a reader of end user R code baffled at first
by all the magic that is going on. Even the R tutorials for beginners should
show a multiple-value return example right at the point where function calls
and return values are first explained.

I really do not understand why the earlier implementation of "multiple-value
returns" was deprecated. then again, I am a naive end user, not a computer
language expert. I probably would not even understand the nuances of syntax
ambiguities that may have arisen. (this is my shortcoming.)

regards,

/iaw


On Mar 7, 2009 4:34am, Wacek Kusnierczyk
<Waclaw.Marcin.Kusnierczyk at idi.ntnu.no> wrote:

Mark.Bravington at csiro.au wrote:

The syntax for returning multiple arguments does not strike me as

particularly appealing. ?would it not possible to allow syntax like:

? f= function() { return( rnorm(10), rnorm(20) ) }

? (a,d$b) = f()

FWIW, my own solution is to define a "multi-assign operator":

'%
? # a must be of the form '{thing1;thing2;...}'

? a
? e
? stopifnot( length( b) == length( a))

? for( i in seq_along( a))

? ? eval( call( '
? NULL

}

you might want to have the check less stringent, so that rhs may consist

of more values that the lhs has variables. ?or even skip the check and

assign NULL to a[i] for i > length(b). ?another idea is to allow %
be used with just one variable on the lhs.



here's a modified version:



? ?'%
? ? ? ?a
? ? ? ?if (length(a) > 1)

? ? ? ? ? ?a
? ? ? ?if (length(a) > length(b))

? ? ? ? ? ?b
? ? ? ?e
? ? ? ?for( i in seq_along( a))

? ? ? ? ? ?eval( call( '
? ? ? ?NULL }



? ?{a; b} %
? ?# a = 1; b = 2

? ?a %
? ?# a = 3

? ?{a; b} %
? ?# a = 5; b = NULL





vQ