Re: [Rd] Bug in new() or validObject() in methods package (PR#7922)

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Mon 06 Jun 2005 - 20:57:37 GMT

On 6/6/2005 4:55 PM, Peter Dalgaard wrote:

> murdoch@stats.uwo.ca writes:
> 

>> Is it doing an extra eval or something? It looks like it:
>>
>> > x <- expression()
>> > x
>> expression()
>> > eval(x)
>> NULL
>> >
>> > x <- quote(expression())
>> > x
>> expression()
>> > eval(x)
>> expression()
>> > eval(eval(x))
>> NULL
> 
> You do realize that the two expression() results are not identical:
> 

>> x <- quote(expression())
>> class(x)
> [1] "call"

>> x <- expression()
>> class(x)
> [1] "expression"
> 
> Not that I can fathom what bearing that has on the real problem...

I figured they weren't identical, given that they gave different results   when eval'd, but I didn't know what the difference was exactly. Thanks!

Duncan



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https://stat.ethz.ch/mailman/listinfo/r-devel Received on Tue Jun 07 07:04:06 2005

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