>>>>> "BDR" == Prof Brian Ripley <[EMAIL PROTECTED]>
>>>>> on Fri, 4 May 2007 22:09:58 +0100 (BST) writes:
BDR> On Fri, 4 May 2007, Simon Urbanek wrote:
>> On May 3, 2007, at 8:52 PM, Deepayan Sarkar wrote:
>>
>>> [...] I have a couple of related questions. First,
>>> dev.interactive (), used in example() and many demo()-s
>>> to decide if the current device is interactive, is
>>> currently implemented as:
>>>
>>>> dev.interactive
>>> function (orNone = FALSE) { iDevs <- c("X11", "GTK",
>>> "gnome", "quartz", "windows", "JavaGD") interactive() &&
>>> (.Device %in% iDevs || (orNone && .Device == "null
>>> device" && getOption("device") %in% iDevs)) }
>>>
>>> This makes it impossible for new devices to be treated
>>> as interactive.
>>
>>
>> I think we should finally pass this question to the
>> device itself. For some devices like Cairo the answer
>> depends on the parameters with which the device was
>> created (e.g. type='x11' is interactive whereas
>> type='png' is not), so each instance of the device will
>> answer differently. We could simply add an another
>> capability flag - that is IMHO the only reliable
>> solution. Any other ideas?
BDR> Do we need a reliable solution? The worst that happens
BDR> that if R thinks a device is interactive and it is not,
BDR> you get asked to go on to the next page a few times.
BDR> I've altered R-devel to look at the displaylist. All
BDR> the devices I knew had that enabled by default iff they
BDR> are screen devices, but I've just looked at Cairo and
BDR> it seems that could be a bit less dumb about its
BDR> setting.
BDR> You can't in general ask the device, as there might be
BDR> no device open and you need to know what the device
BDR> that would automatically opened will do. And you don't
BDR> want to open it, as it might not be needed. Allowing
BDR> devices to say by name that they will be interactive is
BDR> the only way anyone has come up with on this so far.
I agree (particularly about the very logical reason above).
But I tend to agree with Deepayan, that
we should give the useR / programmeR a way to just add a name to
that list (well "readably", i.e. with a selfexplainable function
call).
Even for Cairo, the useR can add "cairo" to that
list when she knows that cairo will be called in X11-mode; or
maybe the cairo "initialization/setup" code code do that
automatically when it's loaded..
Martin
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
