Re: A rant about backward-incompatible changes

[Rob Kendrick <rjek@...>]

On Tue, Jul 14, 2015 at 11:50:44PM +0900, Simon Cozens wrote:
> On 14/07/2015 23:45, Rob Kendrick wrote:
> > Python 3 is not backwards compatible with Python 2.
> 
> Right, but it has a deprecation/future process. ("from __future__
> import...")

That's forwards compatibility.

And Python 3 includes new keywords, so any Python 2 program that uses
them as variable names is shafted.

> > And Perl 5 is not with 4.
> 
> Actually, it is.
> https://en.wikibooks.org/wiki/Perl_6_Programming/Perl_History says,
> correctly, "Through all these developments, Perl has remained backwards
> compatible with previous versions. The Perl 5 interpreter can read,
> understand and execute (for the most part) programs that were written in
> Perl 1, Perl 2, Perl 3 and Perl 4." And there is a test suite for this,
> and a policy:
> http://perldoc.perl.org/perlpolicy.html#BACKWARD-COMPATIBILITY-AND-DEPRECATION

"for the most part".

B.