Re: [ublas] size1 and size2

Subject: Re: [ublas] size1 and size2
From: Curtis Gehman (csgehman_at_[hidden])
Date: 2009-09-13 20:16:21

Just want to voice my opinion on this question of size1() vs. n_rows()  
[or whatever].  I don't really see how "n_rows" or "size_rows" is any  
more user-friendly than size1.  Claiming that they are more  
descriptive assumes a particular interpretation of the matrix indexes-- 
in particular, that the first index is a "row" index).  Though I  
concede that this interpretation is very common, it certainly seems  
plausible that some programmers might find themselves in situations  
where a different interpretation is natural, and the names you suggest  
would actually be much more confusing than the existing ones.

Isn't it pretty clear that size1 gives the size of the matrix in the  
first index?  If it's not obvious, one simple sentence of explanation  
in the API documentation quickly clarifies the usage, and any  
programmer with basic familiarity of STL and aptitude to consider  
using uBLAS will immediately internalize it.  Moreover, size1 is  
completely general; it makes no assumptions about the interpretation  
of the matrix data.  So, if I had a vote, I would vote to keep size1()  
and size2().

Thanks for your consideration.

Curtis Gehman
Burlingame, CA

At Thu, 10 Sep 2009 09:51:03 +0200, Marco Guazzone <marco.guazzone_at_[hidden] 
 > wrote ...

Maybe adding inline methods and free functions with more user-friendly
names like the ones below could be a good idea and does not break
backward-compatibility:

--- [code] ---

// in matrix.hpp

template<...> class matrix:...
{
  BOOST_UBLAS_INLINE
  size_type n_rows() const { return size1_; }
  BOOST_UBLAS_INLINE
  size_type n_columns() const { return size2_; }
};

// same for the other types

// in detail/raw.hpp

template <typename M>
BOOST_UBLAS_INLINE
int n_rows(M const& m ) { return m.n_rows(); }

template <typename M>
BOOST_UBLAS_INLINE
int n_columns( M const& m) { return m.n_columns(); }

template <typename M>
BOOST_UBLAS_INLINE
int n_rows(matrix_reference<M> const& m) { return  
n_rows(m.expression());  }

template <typename M>
BOOST_UBLAS_INLINE
int n_columns(matrix_reference<M> const& m )  { return
n_columns(m.expression());  }

--- [/code] ---

What do you think?