Bug #11230


Should rb_struct_s_members() be public API?

Added by Eregon (Benoit Daloze) over 8 years ago. Updated about 1 year ago.

Target version:
ruby -v:
ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux]


rb_struct_s_members() is declared in include/ruby/intern.h.

However it seems this is a fairly internal API as it returns an hidden Array.

For instance, there was a try to specify the behavior in
but that produces only erratic behavior on MRI because that usage is not intended.

A valid usage might be:

static VALUE get_struct_member(VALUE self, VALUE obj, VALUE i) {
    return RARRAY_AREF(rb_struct_s_members(obj), NUM2INT(i));

p get_struct_member(, :bb), 1)

But do we need such access and is it worth exposing a potentially dangerous function like this?

Updated by jeremyevans0 (Jeremy Evans) almost 3 years ago

At the April 2021 developer meeting, it was decided to remove this C-API function after Ruby 3.2.

Updated by jeremyevans0 (Jeremy Evans) about 1 year ago

I submitted a pull request to remove the prototype from the public header files:

rb_struct_s_members is still an exported symbol as it is used internally by marshal.c.

One of reasons stated to remove this method is that it returns a hidden Array. However, rb_struct_members appears to return the same hidden Array (that method is also used internally by marshal.c). Should we consider removing rb_struct_members from the public API as well?

Updated by mame (Yusuke Endoh) about 1 year ago

Discussed at the dev meeting.

When we considered removing rb_struct_s_members two years ago, we did not find its use in a major gem. Therefore, we agreed to remove it once.

However, two years have passed since then, and now we have found that oj gem is using it.

$ gem-codesearch rb_struct_s_members | sort
2023-02-01 /srv/gems/oj-3.14.1/ext/oj/custom.c:        ma   = rb_struct_s_members(clas);
2023-02-01 /srv/gems/oj-3.14.1/ext/oj/dump_object.c:        VALUE       ma = rb_struct_s_members(clas);
2023-02-01 /srv/gems/oj-3.14.1/ext/oj/rails.c:    ma = rb_struct_s_members(rb_obj_class(obj));

It's possible to fix oj gem and have a deprecation warning period. However, it would be easier to just keep this C API, unless there is a strong reason why we really have to remove it.

Actions #4

Updated by jeremyevans0 (Jeremy Evans) about 1 year ago

  • Status changed from Open to Rejected

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