[#98621] Re: Function getlogin_r()'s protoype] — Bertram Scharpf <lists@...>
FYI,
3 messages
2020/06/02
[#98947] [Ruby master Feature#16986] Anonymous Struct literal — ko1@...
Issue #16986 has been reported by ko1 (Koichi Sasada).
66 messages
2020/06/26
[#98962] [Ruby master Bug#16988] Kernel.load loads file from current directory without '.' in path — misharinn@...
Issue #16988 has been reported by TheSmartnik (Nikita Misharin).
5 messages
2020/06/26
[#98969] [Ruby master Feature#16994] Sets: shorthand for frozen sets of symbols / strings — marcandre-ruby-core@...
Issue #16994 has been reported by marcandre (Marc-Andre Lafortune).
7 messages
2020/06/26
[#100117] [Ruby master Feature#16994] Sets: shorthand for frozen sets of symbols / strings
— matz@...
2020/09/25
Issue #16994 has been updated by matz (Yukihiro Matsumoto).
[ruby-core:98775] [Ruby master Feature#16960] Feedback regarding `=>` in ‘As’ Pattern Matching
From:
paradox.ver5@...
Date:
2020-06-13 00:30:33 UTC
List:
ruby-core #98775
Issue #16960 has been reported by ParadoxV5 (𝕻𝔞𝔯𝔞𝔡𝔬𝔵Ⅴ⓹ ⛥).
----------------------------------------
Feature #16960: Feedback regarding `=>` in ‘As’ Pattern Matching
https://bugs.ruby-lang.org/issues/16960
* Author: ParadoxV5 (𝕻𝔞𝔯𝔞𝔡𝔬𝔵Ⅴ⓹ ⛥)
* Status: Open
* Priority: Normal
----------------------------------------
The only obstacle preventing the use of non-symbol keys in hash patterns is simply the fact that `=>` is used for both `Hash`es and ‘as’ patterns.
```ruby
case x
in Integer => a, Float => b # Ambiguous
in key: Symbol => value, **rest # Poor readability
in Symbol => key => Symbol => value, **rest # ???
end
```
I recommend changing to something else. We can introduce the and operator `&`:
```ruby
case array in Float & 5 & five
five.eql? 5.0 #=> true
end
```
And/Or, implement another operator explicitly for ‘as’ patterns, say `:` (otherwise only used for *the* ternary operation) –
```ruby
case x
in Integer : a, Float : b
in key: Symbol : value, **rest
in Symbol : key => Symbol : value, **rest
end
```
– which renders the pin operator `^` (and for those who *oppose*, their *unpin* operator(s)) unnecessary: expressions before it are always pinned values, and expressions after it are always `case`-`in` variable declarations.
```ruby
good = 8..10
okay = 5..7
skip = 0
case x
in skip : # Syntax sugar for skip : _
# skip
in good : good_value
puts good_value
in okay : okay_value
warn okay_value
else : bad_value # Syntax sugar for BasicObject : bad_value
raise bad_value.to_s
end
```
The second option still looks like an **un**pin operator for sugary code, however, if pinning values –
```ruby
case array
in :, : *all_but_first # Syntax sugar for BasicObject : _, BasicObject : *all_but_first
p all_but_first
end
```
– are somehow preferred over declaring variables:
```ruby
case array
in _, *all_but_first # Current implementation
p all_but_first
end
```
# Regarding `rescue`
We can’t change the `=>` part in `rescue`, of course; but we don’t need to. `Hash`es are not `Exception`s anyway.
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