From: "yui-knk (Kaneko Yuichiro) via ruby-core" <ruby-core@...>
Date: 2025-09-01T03:50:16+00:00
Subject: [ruby-core:123152] [Ruby Feature#17398] SyntaxError in endless method

Issue #17398 has been updated by yui-knk (Kaneko Yuichiro).


> Note that private def hello = puts "Hello" does not parse for technical reason.

It's possible.
Patch is https://github.com/yui-knk/ruby/tree/bug_17398.
This change allows single endless method definition with command body as an argument of the method.
Some cases you might be aware are

* `private :m, def hello = puts "Hello"`
  * This is SyntaxError because only single argument case is allowed.
  * This is same with one command is passed to argument. `obj.m 0, cmd 1, 2` is SyntaxError.
* `private def hello = puts "Hello", "World"`
  * This is interpreted as `private def hello = puts("Hello", "World")` not `private (def hello = puts "Hello"), "World"`.
  * This is same with one command is passed to argument. `obj.m cmd 1, 2` is interpreted as `obj.m cmd(1, 2)` not `obj.m (cmd 1), 2`.
* `private def hello = puts "Hello" do expr end`
  * This is interpreted as `private (def hello = puts "Hello") do expr end` not `private (def hello = puts "Hello" do expr end)`
  * This is same with one command is passed to argument. `obj.m cmd 1, 2 do expr end` is interpreted as `obj.m (cmd 1, 2) do expr end` not `obj.m (cmd 1, 2 do expr end)`

----------------------------------------
Feature #17398: SyntaxError in endless method
https://bugs.ruby-lang.org/issues/17398#change-114484

* Author: zverok (Victor Shepelev)
* Status: Closed
----------------------------------------
This works:
```ruby
def foo() = puts("bar")
```

This does not:
```ruby
def foo() = puts "bar"
#                ^ syntax error, unexpected string literal, expecting `do' or '{' or '('
```

Is this intentional or accidental? Not sure how it is reasoned.

---Files--------------------------------
allow-command-style-endless-method-def.patch (3.44 KB)


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