define_iterator not using passed begin/end

[hsitter]

define_iterator has two arguments for member function pointers to get the beginning respectively end of an iterator. They don't do anything though.

The pointers are passed into the Iterator_Impl and held as members but not ever used. Instead, the Iterator_Impl always calls

    Iterator_T it = obj->begin();
    Iterator_T end = obj->end();

making the originally passed pointers utterly useless.
This is a problem when one needs multiple iterators on the same entity or to wrap a pre-existing data structure which has non-standard begin/end functions.

e.g.

    Data_Type<pkgCache> rb_cPkgCache =
      define_class<pkgCache>("PkgCache")
      .define_iterator(&pkgCache::PkgBegin, &pkgCache::PkgEnd);

results in build error

/home/me/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rice-2.1.1/ruby/lib/include/rice/detail/Iterator.hpp:51:32: error: ‘class pkgCache’ has no member named ‘begin’
     Iterator_T it = obj->begin();
                                ^
/home/me/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rice-2.1.1/ruby/lib/include/rice/detail/Iterator.hpp:52:31: error: ‘class pkgCache’ has no member named ‘end’
     Iterator_T end = obj->end();
                               ^

as the T in question actually doesn't implement begin/end.

Currently, the only way to deal with this seems to be manually implementing a .each or stacking a proxy class on top. Latter still has the problem that one cannot have a second iterator.

[jasonroelofs]

I see what you mean. Thanks for the report. Doesn't look like a tough thing to fix, I'll see what I can do. If you do get a chance to try a fix yourself I'm happy to review as well.