This code doesn't make sense.
123.digits # => [3, 2, 1]New Features in Ruby 2.4
11–20 of 76 posts
Re: New Features in Ruby 2.4
#12> If you are calling #sum on an array of non-integers then you need to provide your own initial value
Why? This doesn't seem necessary, but, more importantly, would be inconsistent with #inject's behaviour (if enforced).
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http://ruby-doc.org/core-2.3.1/Enumerable.html#method-i-inje...:
If you do not explicitly specify an initial value for memo, then the first element of collection is used as the initial value of memo
Re: New Features in Ruby 2.4
#13These improvements feel like amateur hour. No leadership no roadmap no goals.
Re: New Features in Ruby 2.4
#14Some of these are pretty amazing, like the `digits` method and the new OptionParser functionality (which seems to be a sort of standard library equivalent to doctopt!). That being said, I can't help but shake my head at the section about "multiple assignment of conditionals: "You can now assign multiple variables within a conditional...You probably shouldn’t do that though." Am I alone and thinking that it's a little…
Ah well "You probably shouldn’t do that though" is just my opinion as the author. I didn't play a part in these changes. I just like Ruby enough to dig into their changelog :)
Interestingly, assignment inside conditionals is usually avoided because it is easy to accidentally do an assignment (=) rather than a comparison (==). Note that for multiple assignment this mistake can no longer happen:
irb(main): a, b == 3
SyntaxError: syntax error, unexpected ==, expecting '='
Re: New Features in Ruby 2.4
#15This code doesn't make sense. 123.digits # => [3, 2, 1]
Usually when I've seen digits indexed in a number it occurs from right to left (certainly in binary contexts--bit 0 is the least significant bit and bit 31 is the the most significant bit in a 32 bit integer). So, 123.digits[0] means the least significant digit, 3, whereas 123.digits[2] would give you 1, the most significant digit.
Re: New Features in Ruby 2.4
#16> If you are calling #sum on an array of non-integers then you need to provide your own initial value Why? This doesn't seem necessary, but, more importantly, would be inconsistent with #inject's behaviour (if enforced). ---- http://ruby-doc.org/core-2.3.1/Enumerable.html#method-i-inje... : If you do not explicitly specify an initial value for memo, then the first element of collection is used as the initial value of…
I assume (but don't know) that this is an attempt to avoid returning `nil` for empty collections: `[].inject(:+)` is `nil`, but `[].sum` is `0`.
Forcing the use of the additive identity every time, rather than starting with the first element of the collection, is a good way of setting people up to get the correct behaviour on empty collections, even if they don't test for that case.
Re: New Features in Ruby 2.4
#17digits method just saved code-golfers 20 characters. `num.to_s.split(//).map(&:to_i)` => `num.digits`
It's also reverse.
Re: New Features in Ruby 2.4
#18Ruby 2.4 adds a new #match? method for regular expressions which is three times faster than any Regexp method in Ruby 2.3:
Why does Ruby have 4 different regexp match functions?
Regexp#match?: 2630002.5 i/s Regexp#===: 872217.5 i/s - 3.02x slower Regexp#=~: 859713.0 i/s - 3.06x slower Regexp#match: 539361.3 i/s - 4.88x slower
Re: New Features in Ruby 2.4
#19Will this be the last release before 3? Is there a defined schedule for 3 yet? Or just "When it's done"?
Re: New Features in Ruby 2.4
#20Ruby 2.4 adds a new #match? method for regular expressions which is three times faster than any Regexp method in Ruby 2.3: Why does Ruby have 4 different regexp match functions? Regexp#match?: 2630002.5 i/s Regexp#===: 872217.5 i/s - 3.02x slower Regexp#=~: 859713.0 i/s - 3.06x slower Regexp#match: 539361.3 i/s - 4.88x slower
So there is choice of course.
match returns match data, and sets the $~ variable
=== returns true or false, setting the $~ variable
=~ returns integer (position) or nil, setting $~
The newest one match? returns a boolean, not setting $~