R (development) changes in arith, logic, relop with (0-extent) arrays

On Mon, Sep 12, 2016 at 9:51 AM, Radford Neal <radford at cs.toronto.edu>
wrote:

    > But isn't the intent to make it an error later?  So I assume we're
    > debating making it an error, not just a warning.

Yes, that's correct.
But if we have a longish deprecation period (i.e. where there's
only a warning) all important code should have been adapted
before it turns to an error

That might be true for continuously-used code.  But for old scripts
for analysing some dataset that someone decides to run again five
years from now, they will be reduced to trying to guess which version
of R they ran under originally,

In the general case this is true of any packages they use anyway, though.
And if you go back far enough old package versions can't even be installed
for current versions of R.

Results are always contingent on the software, including versions, used to
generate them imho. There are ways to try to address this, but they can be
painful and generally require extra work the author of any 5 year old
script you have in your hands now likely didn't do.

or if they now want to use newer
features, to doing a binary search for the most recent version of R
for which they still work, or of course going through the script
trying to find the problem.

Now you're talking not about running a script, though, but of maintaining
and developing it. I know from personal experience how painful developing
on top of legacy code can be, but nonetheless sometimes It needs to be
maintained and updated.

If you really want absolute safety, that is (more or less) possible, but it
means staying in an old version of R with old package versions. I don't
think the expectation of being guaranteed to be able to use new features
and unmodified legacy code at the same time is reasonable. It's great what
that does happen, but it's a bonus imho, not a requirement.

Best,
~G

This wouldn't be a disaster, but I'm not seeing the magnitude of
benefit that would justify imposing this burden on users.  A language
specification shouldn't really be changing all the time for no
particular reason.

   Radford Neal

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Gabriel Becker, PhD
Associate Scientist (Bioinformatics)
Genentech Research

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