example sources in both Python and C++

[Daniel Berlin]

wmcclain at salamander.com (Bill McClain) writes:

> Here is something for the beginning Python programmer, or
> anyone who wants to compare the language with C++.
> 
> I have put up an astronomical package implemented in both
> Python and C++. It is just a subroutine library and a few
> simple applications, all with console interfaces:
> 
>     http://astrolabe.sourceforge.net/
> 
> This is probably not the best example for language comparison,
> in that most of the code is numerical and would look much
> the same in Fortran. But comparing cronus.py with cronus.cpp
> gives some idea of how tasks are approached in both languages.
> 
> Some notes from the home page:
> 
>   Years ago, I originally wrote the astrolabe routines in C. Now, I
>   always implement in Python first, then make a C++ version as a
>   more-or-less direct translation. The C++ source has a lot of
>   compromises required for compatability with different compilers,
>   which are, however, getting closer to the standard with time.
> 
>   The Python sources are obviously more compact than the C++
>   versions and have less declarative overhead. To me, the most
>   unfortunate aspects of C++ are:
> 
>      * STL containers cannot have initialization lists, meaning that
>        inline data must first be held in C-arrays, then copied to
>        the containers at run-time. I use some macros to make this a
>        bit more natural-looking.

Yes, this sucks.

>      * Template arguments cannot be local types. That means STL
>        containers must use types declared at the outer scope, which
>        is ugly.
Wait, what?
Explain what you mean, this is confusing.
If you mean you can only use types in the outermost, or global scope,
as template arguments, your compiler is severely broken.




>      * Functions may not return multiple values. Where Python can
>        have:
> 
>             ra, dec = func()
> 
>        C++ requires:
> 
>             void func(double &ra, double &dec);
>             double ra, dec;
>             func(ra, dec);
> 
>        ...or a struct for a return value, which would require more
>        declarations. In an alternative C-like language, this would
>        be just as strongly-typed as the function shown above:
> 
>             double, double func()
>             double ra, double dec = func();

You could overload operator , for a tuple like class, and use that

> 
> -Bill
> -- 
> http://www.python.org/mailman/listinfo/python-list