On 04/07/2016 13:47, Ned Batchelder wrote:
On Monday, July 4, 2016 at 6:05:20 AM UTC-4, BartC wrote:
On 04/07/2016 03:30, Steven D'Aprano wrote:
You're still having problems with the whole Python-as-a-dynamic-language
thing, aren't you? :-)
Most Pythons seem to pre-compile code before executing the result. That
pre-compilation requires that operators and precedences are known in
advance and the resulting instructions are then hard-coded before execution.
This is the key but subtle point that all the discussion of parser mechanics
are missing: Python today needs no information from imported modules in
order to compile a file. When the compiler encounters "import xyzzy" in
a file, it doesn't have to do anything to find or read xyzzy.py at compile
time.
Yeah, there's that small detail. Anything affecting how source is to be
parsed needs to known in advance.
If operators can be invented, they will only be useful if they can be
created in modules which you then import and use. But that would mean that
imported files would have to be found and read during compilation, not
during execution as they are now.
This is a huge change.
I've used a kind of 'weak' import scheme elsewhere, corresponding to C's
'#include'.
Then the textual contents of that 'imported' module are read by the
compiler, and treated as though they occurred in this module. No new
namespace is created.
I think that could work in Python provided whatever is defined can
tolerate having copies redefined in each module that includes the same
file. Anything that is defined once and is never assigned to nor
modified for example.
--
Bartc
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