[R] Packages: What expressions are allowed outside/before .First.lib?

[Thomas Lumley]

On Tue, 7 Aug 2001, Henrik Bengtsson wrote:

> Follow up on my own message: I found autoload(), see under Q4 below:
> 

> >
> > Q4. What I really want to do is to declare "modifiers<-" in
> > another package,
> > lets call it, 'myrootlib', which all other libraries we write relies on.
> > Trying
> >
> >   require(myrootlib)  # Declares "modifiers<-"
> >
> >   callMe0 <- function(x)
> >     cat("hey\n")
> >   modifiers(callMe0) <- c("private")
> >
> >   callMe <- function(x)
> >     callMe0(x)
> >   modifiers(callMe) <- c("public")
> >
> > won't work! The reason for this seems to be that the package
> > 'myrootlib' is
> > not loaded (evaluated) until afterwards. This brings up the
> > issues asked in
> > Q1 and Q2. Is there another way to do it or do we have to go back to the
> > approaches explained in Q3, Q2 or even Q1?
> >
> 
> Instead of 'require(myrootlib)' above, it looks like
> 'autoload("modifiers<-", "myrootlib")' would work. Is this a correct way to
> use autoload?
> 

Well, it's valid.  

The current autoload() is really a proof-of-concept and might well get replaced or removed by a more elegant mechanism at some point.  My guess is that the order in which the files are concatenated may actually be more reliable than autoload.

    -thomas

Thomas Lumley			Asst. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle


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