[Python-ideas] Operator as first class citizens -- like in scala -- or yet another new operator?

[David Mertz]

I don't really understand HDL/Verilog, but I've worked with people who do.
In fact, I even wrote a pre-processor that transformed the same DSL to
Python, C++, and Verilog.

In my mind, the HDL use case is FAR too narrow and specialized to warrant a
new arrow operator, let an entirely new parser and semantics around
arbitrary operators. There are several existing dunders that could
plausibly be repurposed already (<<, <<=, <=, etc). Those might look
sightly different than the verilog operators, but that's a very small
price. In fact, just using attributes and assignment is an incredibly low
bar too, and allows whatever overriding you wish.

I just don't buy the idea that such a DSL can only be useful if it spells
'abc <== message' and useless if it spelled the same thing as 'abc <<=
message'.


On Fri, May 24, 2019, 9:06 AM Yanghao Hua <yanghao.py at gmail.com> wrote:

> On Fri, May 24, 2019 at 12:29 PM Greg Ewing <greg.ewing at canterbury.ac.nz>
> wrote:
> >
> > Yanghao Hua wrote:
> > > I have explained the problem of use
> > > descriptors in previous replies, where you cannot have a local signal,
> > > e.g. obj.signal = thing # works, but local_signal = thing # doesn't
> > > work.
> >
> > Maybe you could do something like:
> >
> >     local = Signals()
> >     local.signal1 = ...
> >     local.signal2 = ...
>
> In structure design ... and especially when you design a hardware that
> is meant to be automatically converted into verilog or even logic
> gates, I personally would really want to have a one-to-one
> relationship of the python-objects vs the actual hardware structures.
> The granularity is at signal/bit level. This is why I really think
> giving a special assignment in python which users could override is
> really helpful, rather than having to have this kind of special case:
> if you do "self.abc = thing" descriptor mechanism is invoked, but the
> very next line if you do "abc = thing" ... nothing will happen. This
> special case can be completely removed and having a much better
> conceptual consistency if the "<==" assignment operator always behaves
> the same, doesn't matter if it is "self.abc <== thing" or "abc <==
> thing".
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