[ruby-core:83378] [Ruby trunk Feature#12753] Useful operator to check bit-flag is true or false

Issue #12753 has been updated by matz (Yukihiro Matsumoto).


`has_*` is not acceptable. It's not compatible with other method names.
I vote for `allbit?`, `anybit?` and `nobit?`. I am not sure about plurality though.

Matz.


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Feature #12753: Useful operator to check bit-flag is true or false
https://bugs.ruby-lang.org/issues/12753#change-67339

* Author: tagomoris (Satoshi TAGOMORI)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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Ruby's 0 is truthy value. It's useful for many cases, but it's confusing and I made many bugs when I'm writing code to handle binary data, because my thought is almost same with one to write C code in such situation.

```ruby
n = get_integer_value
if n & 0b10100000
  # code for the case when flag is true
else
  # never comes here :(
end
```

IMO it's very useful to have methods for such use-cases, like `#and?` and `#xor?` (`#or?` looks not so useful... I can't imagine the use case of this operator, but it's better to have for consistency).

```ruby
n = get_integer_value
case
when n.and?(0b10000000)
  # negative signed char
when n.and?(0b01110000)
  # large positive
else
  # small positive
end
```




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