[ruby-core:97723] [Ruby master Feature#16746] Endless method definition

Issue #16746 has been updated by retro (Josef Šimánek).


To be honest, I'm a little confused if this is serious proposal now, since it probably started as a joke and got some attention already at GitHub pull request (https://github.com/ruby/ruby/pull/2996) with mixed attitude.

Anyway for one-line method definitions I like part of https://bugs.ruby-lang.org/issues/5065. It looks "nature" to me since similar syntax is already available for blocks and often is used for one-liners. Ideally scope this syntax only for one-liners.

``` ruby
# original
def value; @val; end

# proposed - is that conflicting one?
def value { @val }
```

Alternatively, since the only use-case I have found in this issue is getter having different method and instance variable names, what about to support this out of attr_reader (and all attr_* friends)?

``` ruby
# few ideas
attr_reader :value, for: :val # reads as -> attribute reader "value" for instance variable "val", probably impossible for multiple definitions on one line
attr_reader value: :val # this would support multiple definitions on one line
```

----------------------------------------
Feature #16746: Endless method definition
https://bugs.ruby-lang.org/issues/16746#change-84933

* Author: mame (Yusuke Endoh)
* Status: Assigned
* Priority: Normal
* Assignee: nobu (Nobuyoshi Nakada)
----------------------------------------
Ruby syntax is full of "end"s.  I'm paranoid that the ends end Ruby.  I hope Ruby is endless.

So, I'd like to propose a new method definition syntax.

```ruby
def: value(args) = expression
```

As you see, there is no "end".

Examples.

```ruby
def: hello(name) =
  puts("Hello, #{ name }")

hello("endless Ruby") #=> Hello, endless Ruby
```

```ruby
def: inc(x) = x + 1

p inc(42) #=> 43
```

```ruby
x = Object.new

def: x.foo = "FOO"

p x.foo #=> "FOO"
```

```ruby
def: fib(x) =
  x < 2 ? x : fib(x-1) + fib(x-2)

p fib(10) #=> 55
```

Limitations.

* `def: foo x = x` is invalid; the parentheses for formal arguments are mandatory.
* `private def: foo = x` is invalid; this method definition cannot be an method argument.

A patch is attached.  No conflicts.

---Files--------------------------------
endless-method-definition.patch (2.47 KB)


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