[R] source(file) => file becomes readonly
murdoch at stats.uwo.ca
Thu Sep 22 02:12:10 CEST 2005
Prof Brian Ripley wrote:
> This was not really accurate.
> Being `read-only' is a Windows phenomenon on open files (even files open
> for reading). In 2.0.1 and 2.1.1 the file was open whilst it was parsed
> and so `read-only' during that time. In 2.0.1 it was then closed, but in
> 2.1.1 it was (potentially) opened several times to find an encoding,
> parsed and left open until source() terminated. In 2.2.0 it will be
> closed once it has been parsed.
But R doesn't open files in an exclusive mode. It opens them in "share
deny none" mode (_SH_DENYNO; this is an undocumented feature of the MSVC
run-time library that MinGW uses). I suspect whatever editor Hjellvik
was using attempted to open the file with exclusive access, and when
that failed (because R had it open), it fell back to read-only access.
It's certainly possible to open a file for write access in another
process while R has it open for read access. You just can't get
exclusive access to it.
> Changing a file after it has been parsed will have no effect, so there is
> no reason to prevent it (beyond that was the simplest way to implement
> choosing a suitable encoding).
> On Thu, 1 Sep 2005, Hjellvik Vidar wrote:
>>The OS is Windows XP.
>>I use to work on the file while it's executed and save changes
>>continually. It doesn't seem to have any effect on the current
>>execution. I just find it annoying not to be able to do it. It's not
>>crucial, but if there is some easy way around it I would like to
>>From: Uwe Ligges [mailto:ligges at statistik.uni-dortmund.de]
>>Sent: 1. september 2005 14:21
>>To: Hjellvik Vidar
>>Cc: r-help at stat.math.ethz.ch
>>Subject: Re: [R] source(file) => file becomes readonly
>>Hjellvik Vidar wrote:
>>>when I work in R, I write code in a text file that I run with the "source(filename)" command. In R2.1.1 the file is read-only while the source command is executed. This was not the case in R2.0.1. Is this a bug-fix or is it possible not to have the file read-only when executed?
>>So you want to modify a file *while* it is executed?
>>Sounds dangerous to me, you may want to explain further...
>>BTW: Which OS are we talking about?
>>>R-help at stat.math.ethz.ch mailing list
>>>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>>R-help at stat.math.ethz.ch mailing list
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