On Thu, May 12, 2011 at 10:55 AM, Henrik Bengtsson <h...@biostat.ucsf.edu>
wrote:
> This might have been discussed before, but below is a
> "not-so-unlikely" use case where the user follows normal procedures,
> updates R to a major release version, and then R crashes:
>
> 1. Use runs R stable (e.g. v2.13.0).
> 2. User installs a package with a namespace, e.g.
> install.packages("fortunes").
> 3. User uses the package and one of the package's objects are assigned
> to the global env, e.g. foo <- fortune.
> 4. The user quits R and stores the session data, e.g. q("yes"). The
> session is stored in users home directory.
> 5. User update to new major release of R (e.g. 2.14.0).
> 6. User starts R. R crashes with "Fatal error: unable to restore
> saved object in .RData" because 'fortunes' is not installed for this
> new version of R. There is also an error message before that
> reporting "Error in loadNamespace(name) : there is no package called
> 'fortunes'".
>
> This can also be reproduced using a single R version as follows:
>
> 1. Start R and do:
> install.packages("fortunes")
> library("fortunes")
> foo <- fortune
> remove.packages("fortunes")
> q("yes")
> 2. Restart R. R crashes.
>
> For a GUI-only user this is complicated, because although the users
> sees the informative error message that "Error in loadNamespace(name)
> : there is no package called 'fortunes'", s/he cannot get to the point
> where it is possible to install that missing package. The key for the
> user is to understand to remove the .RData. In order to do this, s/he
> has to locate that file first.
>
> To simplify this, a few alternatives exists:
>
> 1. R reports the full path to the problematic .RData file.
> 2. R renames the problematic .RData file to
> erroneous_20110512-123404UTC.RData and reports the new full pathname.
>
> In both cases there could be the option for R to either exit, or
> ignore the problematic .RData file and give the user access to the
> prompt. One could also imaging a fancy recovery feature where R
> detects "erroneous" .RData files and asks the user if s/he wish to try
> to load them (maybe the packages has been installed since).
On Windows, the easiest way to give a GUI-only user access to the R
prompt is to also install an "R (vanilla mode)" shortcut/icon on the
Startup menu and Desktop (with target "...\Rgui.exe" --vanilla) in
addition to the default one.
/Henrik
>
> I'm sure there are complications to implement the above, because
> .RData is loaded during startup, but that's my $.02 to this problem
>
> /Henrik
>
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