[#99002] [Ruby master Feature#17004] Provide a way for methods to omit their return value — shyouhei@...

Issue #17004 has been reported by shyouhei (Shyouhei Urabe).

21 messages 2020/07/01

[#99044] [Ruby master Bug#17007] SystemStackError when using super inside Module included and lexically inside refinement — eregontp@...

Issue #17007 has been reported by Eregon (Benoit Daloze).

7 messages 2020/07/03

[#99078] [Ruby master Feature#17016] Enumerable#scan_left — finch.parker@...

Issue #17016 has been reported by parker (Parker Finch).

42 messages 2020/07/07

[#99079] [Ruby master Bug#17017] Range#max & Range#minmax incorrectly use Float end as max — bosticko@...

Issue #17017 has been reported by sambostock (Sam Bostock).

25 messages 2020/07/07

[#99097] [Ruby master Bug#17021] "arm64" and "arm" are mixed in RbConfig on Apple silicon — watson1978@...

Issue #17021 has been reported by watson1978 (Shizuo Fujita).

9 messages 2020/07/09

[#99115] [Ruby master Bug#17023] How to prevent String memory to be relocated in ruby-ffi — larskanis@...

Issue #17023 has been reported by larskanis (Lars Kanis).

22 messages 2020/07/10

[#99156] [Ruby master Bug#17030] Enumerable#grep{_v} should be optimized for Regexp — marcandre-ruby-core@...

Issue #17030 has been reported by marcandre (Marc-Andre Lafortune).

25 messages 2020/07/13

[#99257] [Ruby master Misc#17041] DevelopersMeeting20200826Japan — mame@...

Issue #17041 has been reported by mame (Yusuke Endoh).

18 messages 2020/07/22

[#99308] [Ruby master Feature#17047] Support parameters for MAIL FROM and RCPT TO — bugs.ruby-lang.org@...

Issue #17047 has been reported by c960657 (Christian Schmidt).

11 messages 2020/07/23

[#99311] [Ruby master Bug#17048] Calling initialize_copy on live modules leads to crashes — XrXr@...

Issue #17048 has been reported by alanwu (Alan Wu).

17 messages 2020/07/24

[#99351] [Ruby master Bug#17052] Ruby with LTO enabled on {aarch64, ppc64le} architectures. — v.ondruch@...

Issue #17052 has been reported by vo.x (Vit Ondruch).

35 messages 2020/07/27

[#99375] [Ruby master Feature#17055] Allow suppressing uninitialized instance variable and method redefined verbose mode warnings — merch-redmine@...

Issue #17055 has been reported by jeremyevans0 (Jeremy Evans).

29 messages 2020/07/28

[#99391] [Ruby master Feature#17059] epoll as IO.select — dsh0416@...

Issue #17059 has been reported by dsh0416 (Delton Ding).

18 messages 2020/07/29

[#99418] [Ruby master Feature#17097] `map_min`, `map_max` — sawadatsuyoshi@...

Issue #17097 has been reported by sawa (Tsuyoshi Sawada).

11 messages 2020/07/31

[ruby-core:99040] [Ruby master Feature#17004] Provide a way for methods to omit their return value

From: merch-redmine@...
Date: 2020-07-02 21:11:05 UTC
List: ruby-core #99040
Issue #17004 has been updated by jeremyevans0 (Jeremy Evans).


marcandre (Marc-Andre Lafortune) wrote in #note-19:
> jeremyevans0 (Jeremy Evans) wrote in #note-13:
> > Due to Sequel::Dataset#insert's flexible API, it would be hard to support this as a method argument.
> 
> Seems to be that a better API for this is using a block parameter.
> 
> ```ruby
> # need the ID:
> insert(...) do |last_inserted_id|
>   # ...
> end
> 
> # don't need the ID:
> insert(...)
> ```

Sequel::Dataset#insert already accepts a block, which can be used to iterate over rows returned from the insert statement (when using INSERT RETURNING).

> 
> Another possibility is to implement a lazy return value, something like:
> 
> ```ruby
> class LazyID
>   def to_i
>     # get the ID
>   end
> end
> 
> def insert(...)
>   # ...
>   LazyID.new(self)
> end
> ```

In general, this approach requires additional allocation in the case where you are using the return value, decreasing performance.  In this particular case, it's not possible, because you would probably lose access to the database connection used to insert the record before calling `LazyID#to_i`, and that database connection is needed to get the value.

----------------------------------------
Feature #17004: Provide a way for methods to omit their return value
https://bugs.ruby-lang.org/issues/17004#change-86415

* Author: shyouhei (Shyouhei Urabe)
* Status: Open
* Priority: Normal
----------------------------------------
In ruby, it often is the case for a method's return value to not be used by its caller.  Even when a method returns something meaningful, its caller is free to ignore it.

Why not provide a way for a method to know if its return value is needed or not?  That adds a room for methods to be optimized, by for instance skipping creation of complex return values.

The following pull request implements `RubyVM.return_value_is_used?` method, which does that: https://github.com/ruby/ruby/pull/3271



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