anything like C++ references?

Stephen Horne intentionally at blank.co.uk
Thu Jul 17 01:09:13 CEST 2003


On Wed, 16 Jul 2003 22:00:22 +0000 (UTC), Adam Ruth
<owski at hotmail.com> wrote:

>In <8sdbhvk5b5ia2onmbca4ajkaidpu3ht9ed at 4ax.com> Stephen Horne  wrote:
>> On Wed, 16 Jul 2003 19:06:40 +0000 (UTC), Adam Ruth
>> <owski at hotmail.com> wrote:
>> 
>>>You are correct in that there are times when pointer semantics would 
>>>be  somewhat useful, but they're never necessary.  His statement was 
>>>that  there are time that "you really can't avoid pointers".
>> 
>> Hmmm - those words were in a context. I never claimed that "you really
>> can't avoid pointers" in *current* Python - that's obviously not true.
>> But if the copy-on-write stuff were implemented, the need would arise.
>> For example...
>
>It sure seemed that way to me:
>
><prior dicussion>
>>>They're an unhappy necessity, akin to stop-lights.  You need them
>>>because roads intersect, but if roads don't intersect, don't use them!
>>
>>Absolutely true. And the worst thing you can do when you really can't
>>avoid pointers is to obscure the issue even more by disguising them as
>>something else.
></prior discussion>

Right - "the worst thing you can do when you really can't avoid
pointers" is not the same as "really can't avoid pointers".

You have taken the condition out of a conditional scentence and quoted
it as if it were a statement. That's a pretty clear case of quoting
out of context to misrepresent what someone said, isn't it.

Now lets restore the rest of what Adam said...

: I came to Python from Ada, and all I have to say is:  Pointer-like
: semantics are evil.  They're worse than goto's, they're deadly,
: damaging, and should be avoided at all costs.
: 
: They're an unhappy necessity, akin to stop-lights.  You need them
: because roads intersect, but if roads don't intersect, don't use them!

Guess what - when Adam said pointers are an 'unhappy necessity' he was
talking about ADA - NOT PYTHON. In Ada, pointers (or rather access
types) are definitely not overused (where I worked you needed
management permission and a damned good reason to use them due to the
military contract terms), but sometimes they are unavoidable.


Please be more careful what you snip.

>The reference is passed by value 
>to the function, just as you describe it should.

Yes - there has to be pass-by-value at some level since Python is
implemented in C. But to me this just says that we are seeing the
side-effect of an implementation detail.

No need to argue this - you don't need to explain it to me because I
understand. It just see things from a different perspective.

  Python, however, has a 
>futher layer of abstraction on top of its one data type, and that's 
>objects.  I would venture that it's the extra layer of abstraction that 
>makes Python work in a more intuitive, proper way.
>
>This is, however, just my opinion.  But it does seem that new 
>programmers who learn this abstraction find it natural and simple.  It's 
>people coming from C, et al., that seem thrown off by it.

No, my background isn't just in C - that is a long way from being the
first language I used, and I've used Python regularly longer than C++.

>As a side note, based on your description of your eduction and studies 
>in an earlier post, I realize now how different our backgrounds seem to 
>be.  I'm coming from a world where the focus is engineering (Ada is the 
>only language purpose-built for engineering, AFAIK).  You seem to come 
>from a background more focused on science and theory.

Nope - I just happen to be interested in learning the theory too, and
particularly in experiencing a broad range of languages to understand
the ideas behind them.

How come you didn't notice ada in my list?

About the first half of my programming career was working in the
defence industry as a software engineer. A lot of that was working at
very low level stuff (the 80c196kc microcontrollers I mentioned) and
with a lot of messing around with target hardware and in-circuit
emulators. The rest of my time in defence was spent using Ada.

I first messed around with writing my own language quite young, with
an Atari ST. I liked the idea of text adventures and decided to write
one, but basically got caught up in the engine and the scripting
stuff. Pretty cool, though, through the rose-tinted glasses of memory.

Anyway, I stayed interested in compilers and stuff, but the reason I
got interested in LR and parsing theory has little to do with parsing
as most see it. A grammar, seen as describing a sequence of tokens,
can deal with many things - the tokens don't have to be words. They
might be events, for instance. And the state of the 'parser' may be
used to select a response strategy in an AI. I wanted it for a game I
was going to write a few years back which would construct strategies
from various elements by building them into a kind of grammar, and use
the resulting state model as a real time AI.

>Perhaps this is 
>the cause of our different world views (on this issue).  Just a thought, 
>though it is interesting we both chose Python.

Strictly speaking, the reason I chose Python at the time was because
at work we used macs with terminal emulators. If you wanted a utility,
you either wrote it under VMS or you were stuffed as mac interpreters
and compilers were hard to come by.

I see it as one of the happiest flukes - I just wish I'd found Python
earlier.





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