[Rd] Error condition in evaluating a promise

[Seth Falcon]

Simon Urbanek <simon.urbanek at r-project.org> writes:
> thanks, but this is not what I want (the symbols in the environment  
> are invisible outside) and it has nothing to do with the question I  
> posed: as I was saying in the previous e-mail the point is to have  
> exported variables in a namespace, but their value is known only  
> after the namespace was attached (to be precise I'm talking about  
> rJava here and many variables are valid only after the VM was  
> initialized - using them before is an error). 

We have a similar use case and here is one workaround:

Define an environment in your name space and use it to store the
information that you get after VM-init.

There are a number of ways to expose this:

* Export the env and use vmEnv$foo

* Provide accessor functions, getVmFooInfo()

* Or you can take the accessor function approach a bit further to make
  things look like a regular variable by using active bindings.  I can
  give more details if you want.  We are using this in the BSgenome
  package in BioC.

HTH,

+ seth