Issue #15723 has been updated by ttilberg (Tim Tilberg).


I've been following this for a while, hopeful that it (or something quite similar) stays in. I've grown to appreciate thinking of the `@1` in a sense of "an instance var of this block", since `@1` can't exist in code today. 

However, I think that strictly using `@` over `@1, @2` will be better. I just came across this thought 

```
array_of_hashes.each { @1.transform_keys { @1.gsub('the_', '')} }     # @1.... was already "assigned" ???
```

If you end up having nested blocks as above, the concept of `@1, @2` feels awkward because of lexical scoping rules with variable names. I think if we removed this idea of `@1` meaning a specific, positional arg, and instead just let it be `@` to be a sygil that mean "this block's default arg", it is less jarring.


For whatever reason, this feels more acceptable:

```
array_of_hashes.each {@.transform_keys {@.gsub('the_', '')} }    # @ wasn't already assigned, as it doesn't mean the same as a named variable.
```

I also think that `@1` gets a lot of value, and `@2 +` quite a bit less so. This adds to my thoughts on simply `@`.

----------------------------------------
Misc #15723: Reconsider numbered parameters
https://bugs.ruby-lang.org/issues/15723#change-79075

* Author: sos4nt (Stefan Schler)
* Status: Feedback
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
----------------------------------------
I just learned that *numbered parameters* have been merged into Ruby 2.7.0dev.

For readers not familiar with this feature: it allows you to reference block arguments solely by their *index*, e.g.

```ruby
[1, 2, 3].each { |i| puts i }

# can become

[1, 2, 3].each { puts @1 }
```

I have an issue with this new feature: I think **it encourages sloppy programming** and results in **hard to read code**.

---

The [original proposal](https://bugs.ruby-lang.org/issues/4475) was to include a special variable (or keyword) with a **readable name**, something like:

```ruby
[1, 2, 3].each { puts it }

# or

[1, 2, 3].each { puts this }
```

Granted, that looks quite lovely and it actually speaks to me  I can *understand* the code. And it fits Ruby: (quoting the website)

> [Ruby] has an elegant syntax that is natural to read and easy to write.

But the proposed `it` / `this` has limited application. It's only useful when dealing with a single argument. You can't have multiple `it`-s or `this`-es. That's why `@1`, `@2`, `@3` etc. were chosen instead.

However, limiting the usefulness to a single argument isn't bad at at. In fact, a single argument seem to be the limit of what makes sense:
```
h = Hash.new { |hash, key| hash[key] = "Go Fish: #{key}" }

# vs

h = Hash.new { @1[@2] = "Go Fish: #{@2}" }
```
Who wants to read the latter? That looks like an archaic bash program (no offense). We already discourage Perl style `$`-references: (from [The Ruby Style Guide](https://github.com/rubocop-hq/ruby-style-guide#no-perl-regexp-last-matchers))

> Don't use the cryptic Perl-legacy variables denoting last regexp group matches (`$1`, `$2`, etc). Use `Regexp.last_match(n)` instead.

I don't see how our code can benefit from adding `@1` and `@2`.

Naming a parameter isn't useless  it gives context. With more than one parameter, naming is crucial. And yes, naming is hard. But avoiding proper naming by using indices is the wrong way.

So please reconsider numbered parameters.

Use a readable named variable (or keyword) to refer to the first argument or ditch the feature entirely.

---Files--------------------------------
implicit-param.diff (20 KB)


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