[Boost][BGL] What are the correct vertex/edge index types?

From: hermann_at_[hidden]
Date: 2024-10-15 08:04:03

First I looked in graph/test.
Most times int is used there, only once std::size_t:

property< edge_index_t, int >

Next I looked into graph/example, same picture there.

Ok, I read that example and test might contain stuff that
would not go into BGL code.
So I looked into graph/include/boost/graph:

pi_at_raspberrypi5:~/graph/include/boost/graph $ grep edge_index_t *.hpp | 
grep size_t
directed_graph.hpp:    typedef std::size_t edge_index_type;
undirected_graph.hpp:    typedef std::size_t edge_index_type;
pi_at_raspberrypi5:~/graph/include/boost/graph $ grep edge_index_t *.hpp | 
grep unsigned
directed_graph.hpp:    typedef property< edge_index_t, unsigned, 
edge_property_type >
undirected_graph.hpp:    typedef property< edge_index_t, unsigned, 
edge_property_type >
pi_at_raspberrypi5:~/graph/include/boost/graph $ grep edge_index_t *.hpp | 
grep int
graphviz.hpp:                   property<edge_index_t, int> >
pi_at_raspberrypi5:~/graph/include/boost/graph $

Only graphviz.hpp uses int.
But directed and undirected graph use std::size_t as well as unsigned.

There are systems when unsigned is smaller than std::size_t:

https://en.cppreference.com/w/cpp/types/size_t

1)
Shouldn't at least directed_graph.hpp and undirected_graph.hpp
make consistent use of std::size_t then?

2)
Shouldn't examples and tests be corrected, as their overly use
of int for edge and vertex index types is misleading?

Regards,

Hermann.