Issue #12752 has been updated by Yusuke Endoh.


There is more concise way:

    length, = str.unpack('C')

You cannot use this in a method chain, though.

I actually understand your frustration, but I feel no difference between `str.unpack('C', 0)` and `str.unpack('C')[0]`.

-- 
Yusuke Endoh <mame / ruby-lang.org>

----------------------------------------
Feature #12752: Unpacking a value from a binary requires additional '.first'
https://bugs.ruby-lang.org/issues/12752#change-60494

* Author: Satoshi TAGOMORI
* Status: Open
* Priority: Normal
* Assignee: 
----------------------------------------
When I parsed a binary protocol (msgpack) by `String#unpack`, there are many similar expressions, like below:

```ruby
str = io.read(1)
length = str.unpack('C').first
case length
when 4
  data = io.read(4).unpack('N').first
# ...
```

I know that `unpack` returns "1 or more" values, but I think there are too many cases to return just one object.
Creating Array objects for return values requires additional cost to create Array object, and calling `.first`.

I'm happy if I can write the code above like this:

```ruby
str = io.read(1)
length = str.unpack('C', 0) # index, or str.unpack('C', index: 0)
case length
when 4
  data = io.read(4).unpack('N', 0)
# ...
```



-- 
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