Regular expression code implementation review between Tcl vs Python

Alex Martelli aleax at aleax.it
Wed Nov 12 12:25:07 CET 2003


Rainer Deyke wrote:

> Alex Martelli wrote:
>> Using an OO language doesn't necessarily make implementing another
>> OO language any easier, when the object models are mismatched (and
>> they almost invariably are).
> 
> Using RAII to automate reference count management would certainly help in
> implementing Python, even if it is a feature that Python itself doesn't
> have.

Yes, C++ surely has plenty of features -- including RAII, templates,
etc -- that might come in useful, quite apart from Python and/or C++
"being OO".  You can see that in extensions written with "Boost
Python" -- you end up using _FAR_ less boilerplate, both for reference
counting and other housekeeping and interfacing tasks.

However, for the size and speed of the resulting code you end up
somewhat at the mercy of your C++ compiler, and I'm not sure they're
anywhere near as optimized as C compilers, yet -- it IS a MUCH larger
and more complicated language, after all.

The problems that C++'s size and complication give to its compilers
(and may, by now, be overcome in the very best compilers -- I do
believe that after these many years there ARE compilers which do
claim 100% compliance with the standard, for example, though I don't
know about quality of optimization) pair up with those given to its
users -- the price to pay for that wonderful plenty of features, of
course, and the awesome _potential_ for speed (even though there may
be yet some time to wait until the full extent of that potential is
actualized by super optimizers).

There's a long-standing debate on whether big languages can be
effectively subsetted, identifying a set of features that can be
counted on to be solidly and optimally implemented on all the
relevant compilers and ensuring no features outside that set are
ever used -- thus allowing programmers to only learn "half" the
language, or some such fraction.  I believe this doesn't work,
except perhaps in a tightly knit group of Extreme Programmers who
are really keen to enforce the group-mandated subsetting rules --
and even then, slight mistakes may end up in "correct" code that
however strays from the blessed subset and produces symptoms which
you need complete knowledge of the language to understand.

So, my opinion is that if an open-source project adopted C++, it
would basically require contributors to make the effort to learn
the whole C++ language, not just half of it.  _Some_ OS projects,
such as Mozilla or KDE, appear to thrive on C++, I believe, and
enforce SOME subsetting effectively.  I'm not sure exactly what
dynamics are at play there, since I'm not a part of those projects.
Still, C still dominates the opensource scene -- C++ has a much
smaller presence there.


Alex





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