From murdoch.duncan at gmail.com  Wed Jan 12 10:33:15 2011
From: murdoch.duncan at gmail.com (Duncan Murdoch)
Date: Wed, 12 Jan 2011 04:33:15 -0500
Subject: [Rd] as.environment.list provides inconsistent results under
 torture
In-Reply-To: <alpine.DEB.2.00.1101111751380.1812@luke-inspiron>
References: <4D2CB092.6000303@r-enthusiasts.com>	<792C6196-A236-44AC-B734-E38A09791CB4@r-project.org>
	<alpine.DEB.2.00.1101111751380.1812@luke-inspiron>
Message-ID: <4D2D755B.1080007@gmail.com>

On 11-01-11 6:55 PM, luke-tierney at uiowa.edu wrote:
> No. Lots of internal functions expect their callers to protect their
> arguments, for efficiency reasons. eval is called very often and
> almost always with argument that are protected because they are in the
> evaluation engine, so it would be wasteful and potentially very costly
> if eval protected its arguments every time it is called. (I don't
> tknow what the cost would be to do so in the current implementation
> but it could be prohibitive if we moved to some different approaches,
> so for now we whould continue to expect callers of eval to make sure
> the argumetns are protected.)

Do we have an isProtected() function to use in debugging?  It should 
check if something is in the protection stack or is protected for some 
other reason, so it doesn't look trivial to write.

Duncan Murdoch


>
> Best,
>
> luke
>
> On Tue, 11 Jan 2011, Simon Urbanek wrote:
>
>> Interesting, I'd argue that the bug is in eval() not protecting its arguments since the usual convention is for functions to protect its arguments...
>>
>> On Jan 11, 2011, at 2:33 PM, Romain Francois wrote:
>>
>>> Hello,
>>>
>>> Using R-devel (rev 53950), I get inconsistent results with as.environment( VECSXP ) when gctorture is on.
>>>
>>> Consider:
>>>
>>> a<- list( aa = rnorm, bb = runif )
>>> gctorture(TRUE)
>>> as.environment( a )
>>>
>>> The last line sometimes produces the correct environment, but sometimes I get errors. Here are the three situations:
>>>
>>> # good
>>>> as.environment( a )
>>> <environment: 0x100b1c978>
>>>
>>> # not good
>>>> as.environment( a )
>>> Erreur dans length(x) : 'x' est manquant
>>>
>>> # not good either
>>>> as.environment( a )
>>> Erreur dans list(NULL, list(aa = function (n, mean = 0, sd = 1)  :
>>>   correspondance partielle de cha?nes de caract?res incorrecte
>>>
>>>
>>> Is it because the call made by lang4 is not protected while evaluated in this line :
>>>
>>>     case VECSXP: {
>>> 	/* implement as.environment.list() {isObject(.) is false for a list} */
>>> 	return(eval(lang4(install("list2env"), arg,
>>> 			  /*envir = */R_NilValue, /* parent = */R_EmptyEnv),
>>> 		    rho));
>>>     }
>>>
>>>
>>> (BTW, this was detected in a looooooooong Rcpp-devel thread. See http://comments.gmane.org/gmane.comp.lang.r.rcpp/1336)
>>>
>>> Romain
>>>
>>> --
>>> Romain Francois
>>> Professional R Enthusiast
>>> +33(0) 6 28 91 30 30
>>> http://romainfrancois.blog.free.fr
>>> |- http://bit.ly/fT2rZM : highlight 0.2-5
>>> |- http://bit.ly/gpCSpH : Evolution of Rcpp code size
>>> `- http://bit.ly/hovakS : RcppGSL initial release
>>>
>>> ______________________________________________
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>>
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>
>
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel



[Rd] as.environment.list provides inconsistent results under torture
Duncan Murdoch