Re: [eigen] On a flexible API for submatrices, slicing, indexing, masking, etc.

[Massimiliano Janes <max.jns@xxxxxxxxx>]

Regarding your example, it actually boils down to:

A( 5 <= iota*2+1 <= 9 ) // all odd numbers between 5 and 9 inclusive

I know ( I was an APL fan when I was younger … :) ), they do define the same progression, but IMO they are not quite equivalent

from a coding point of view; for example, let’s say you start from an _expression_ like

A( 5 <= iota <= 9 )

and later on you want to add some further constraints in the least error prone way … this is what I meant by composable.

Yes, writing _expression_ templates to automatically parse it in some kind of primitive/optimal progression may be tricky

,but not impossible, unless I’m missing something.

The thing I mostly hate about python-range-like gymnastics is that they’re easy to write but so error prone to read and modify,

probably because they focus on the how rather than the what.

this only works with literals, does not work with, e.g.,  template<int Dim> .... then pass Dim as compile-time

I see, yet I see no harm in using a completely different syntax in that case, isn’t it ?