On Friday, January 16, 2015 at 7:20:13 AM UTC+5:30, Andrew Robinson wrote:
<snipped 542 lines>
Disclaimers
1. Ive not really read the above 542 lines and earlier
2. I am not a fan of OOP
Still some thoughts...
Electrical engineering (EE) and computer science (CS) may seem related
but are quite different disciplines. In fact there is some amount of
'client-supplier' in this relation - you folks make the machines we use.
Now one of the basic things that needs to be effected to make this transition
is the so-called digital abstraction
To start with we say (say) that 0V is 0-logic, 3.3V is 1-logic.
But that's hardly enough, we need margins, forbidden regions, Postel's law
etc. This mapping is hardly straightforward. And that is still the
'static-discipline'.
When time comes in we need to deal with the fact that when a gate
switches it will willy-nilly go through the forbidden region. From here
we have to go through/into clock disciplines, delay insensitie circuits etc.
Should CS-ists deal with all this??
If you say yes then what are you EE-guys doing?
If no then you are agreeing with all the others here.
In some more detail:
You seem to want a multi-valued logic. How many values?
There are quite a few answers:
- 4 -- {0,1,Z,X} - http://en.wikipedia.org/wiki/Four-valued_logic
- 9 -- above + weak drives http://en.wikipedia.org/wiki/IEEE_1164
And probably half a dozen others.
You say you REALLY NEED these in your work.
Yes, many people need many things, eg.
1. Mars orbiter was lost due to a mismatch of MKS and FPS systems
http://edition.cnn.com/TECH/space/9909/30/mars.metric.02/
Does that make a case for building in units into programming languages?
2. C.A.R Hoare said the invention of the null-pointer was a billion-dollar
mistake. Do C programmers agree with him?
3. He also considered exception handling as a terrible disaster since it
confuses flow of control. Are python (or most modern language) users likely
to agree?
All these are instances of a basic principle that Niklaus Wirth enunciated:
The most important decision of a language designer are what to leave out
of the language.
Finally in python 3.4 onwards there are enums. You can do this
>>> from enum import IntEnum
>>> class Bool4(IntEnum):
... F=0
... T=1
... Z=2
... X=3
--
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