[Rd] C-API: check whether R has been initialized ?

[Duncan Murdoch]

On 03/05/2015 7:02 PM, Laurent Gautier wrote:
> Beside the possible argumentation that with an API elegance and
> convenience might sometimes be superior to necessity, the suggested
> pattern ("every program, including R itself, keeping its own flag") does
> no work too well when the nested embedding of R is involved.
> 
> A concrete example is:
> ```
> $ R -q
>> library('rPython'); python.exec('import rpy2.robjects')
> R is already initialized
> ```

I don't know rPython at all, but surely this is an rPython bug.  When
the package is loaded by "library('rPython')", R is obviously
initialized.  You don't need to query it to ask that.

The standard R front-ends don't need a flag to know if it is
initialized.  They initialize, then go into the read-eval-print loop.
If they are in that loop, R is initialized.  If it failed to initialize,
they would never get to that loop.

Other front-ends may do other things besides run R, so they do need to
know if it is initialized, but surely they can keep a flag telling them
whether they've succeeded in initializing it.

Duncan Murdoch