[OT] fortran lib which provide python like data type

Rustom Mody rustompmody at gmail.com
Fri Jan 30 18:31:34 CET 2015


On Friday, January 30, 2015 at 10:39:12 PM UTC+5:30, Michael Torrie wrote:
> On 01/30/2015 09:27 AM, Rustom Mody wrote:
> > ... if I restate that in other words it says that sufficiently
> > complex data structures will be beyond the reach of the standard
> > RAII infrastructure.
> > 
> > Of course this only brings up one side of memory-mgmt problems
> > viz. unreclaimable memory.
> > 
> > What about dangling pointers?
> > C++ apps are prone to segfault. Seems to suggest
> > (to me at least) that the memory-management infrastructure
> > is not right.
> > 
> > Stroustrup talks of the fact that C++ is suitable for lightweight
> > abstractions. In view of the segfault-proneness I'd say they 
> > are rather leaky abstractions.
> > 
> > But as I said at the outset I dont understand C++
> 
> Yes I can tell you haven't used C++.  Compared to C, I've always found
> memory management in C++ to be quite a lot easier. The main reason is
> that C++ guarantees objects will be destroyed when going out of scope.

I hear you and I trust you as a gentleman but I dont trust C++ :-)

The only time in some near 15 years of python use that
I got it to segfault was when Ranting Rick gave some wx code to try
[at that time he was in rant-against-tk mode]
Sure enough it was related to the fact that wx is written in C++
and some expectations were not being followed.

> So when designing a class, you put any allocation routines in the
> constructor, and put deallocation routines in the destructor.  And it
> just works.  This is something I miss in other languages, even Python.
> 
> And for many things, though it's not quite as efficient, when dealing
> with objects you can forgo pointers altogether and just use copy
> constructors, instead of the
> 
> blah *a = new blah_with_label("hello") //allocate on heap
> //forget to "delete a" and it leaks the heap *and* anything
> //that class blah allocated on construction.
> 
> just simply declare objects directly and use them:
> 
> blah a("hello") //assuming there's a constructor that takes a string
>                 //deletes everything when it goes out of scope
> 
> So for the lightweight abstractions Stroustrup talks about, this works
> very well. And you'll rarely have a memory leak (only in the class
> itself) and no "dangling pointers."

And what about the grey area between lightweight and heavyweight?

You say just use copy constructors and no pointers.
Can you (ie C++) guarantee that no pointer is ever copied out of 
scope of these copy-constructed objects?

> 
> For other things, though, you have to dynamically create objects.  But
> the C++ reference-counting smart pointers offer much of the same
> destruction semantics as using static objects.  It's really a slick
> system.  Almost makes memory management a non-issue.  Circular
> references will still leak (just like they do on Python).  But it
> certainly makes life a lot more pleasant than in C from a memory
> management perspective.




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