Bug #16127: Delegates to BasicObject do not work

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.0dev (2019-08-25) [x86_64-openbsd6.5]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN

[jeremyevans0 (Jeremy Evans)]

The delegate library does not currently handle BasicObject targets, since it assumes the target responds to respond_to?. The attached patch works around the issue by binding the Kernel respond_to? instance method to the target and then calling that.

[decuplet (Nikita Shilnikov)]

With UnboundMethod#bind_call added in https://bugs.ruby-lang.org/projects/ruby-trunk/repository/git/revisions/83c6a1ef454c51ad1c0ca58e8a95fd67a033f710, we should be able to save some allocations by assigning ::Kernel.instance_method(:respond_to?) to a constant and calling with .bind_call. WDYT? Not a big deal, I just don't like the idea we allocate objects when merely calling a method.

[jeremyevans0 (Jeremy Evans)]

Sure, it would be fine to use #bind_call for this. At the time this patch was submitted, #bind_call wasn't available. I know I have a patch in #7833 where #bind_call could also be applied. We should probably do a sweep for other places in stdlib where #bind_call could be used.

[alanwu (Alan Wu)]

It might be useful to have a test where the delegation happens successfully.

[jeremyevans0 (Jeremy Evans)]

• File delegate-basicobject-16127-v2.patch delegate-basicobject-16127-v2.patch added

Here's an updated patch that uses #bind_call and tests successful delegation to a BasicObject target.

• Status changed from Open to Closed

Applied in changeset git|2322c94dd65c0247b103e2f91411e37458e1466d.

---

Support delegates for BasicObject

For BasicObject, bind the Kernel respond_to? instance method to the
object and call it instead of calling the method directly.

Also, use bind_call(recv, ...) for better performance.

Fixes [Bug #16127]