New features in Ruby 2.5. New methods & performance improvements and other notable changes.

1. RUBY 2.5
IRENEUSZ SKROBIŚ
Lead developer @ SELLEO

2. AGENDA

3. AGENDA
new features

4. AGENDA
new features
performance
improvements

5. AGENDA
new features
performance
improvements
other notable
changes

6. New features
1

7. rescue/else/ensure are now allowed
to be used directly with do/end blocks
AFTER:
lambda do
raise 'err'
rescue
$! # => #<RuntimeError: err>
end.call
BEFORE:
lambda do
begin
raise 'err'
rescue
$! # => #<RuntimeError: err>
end
end.call

8. Add yield_self to yield given block in its context
class Object
def yield_self(*args)
yield(self, *args)
end
end
2.yield_self { |x| x*x } # => 4

9. Hash#slice & Hash#except
{ a: 1, b: 2, c: 3, d: 4 }.slice(:a, :b)
# => { a: 1, b: 2 }
{ a: 1, b: 2, c: 3, d: 4 }.except(:a, :b)
# => { c: 3, d: 4 }

10. Hash#transform_keys
{ a: 1, b: 2 }.transform_keys { |k| k.to_s }
=> { "a"=>1, "b"=>2 }

11. Struct.new can create classes that accept keyword arguments
Point = Struct.new(:x, :y, :color)
point1 = Point.create(x: 1, y: 2)
# => Point<x: 1, y: 2, color: nil>
point2 = Point.create!(x: 1, y: 2)
# => ArgumentError, color not specified.

12. Enumerable#any?, all?, none?, and one? accept a pattern argument
[1, 3.14, 2ri].all?(Numeric) # => true
if should_be_all_symbols.any?(String)
...
end
some_strings.none?(/aeiou/i)

13. Array#prepend/append as aliases of unshift/push
array = [3, 4]
array.prepend(1, 2) #=> [1, 2, 3, 4]
array #=> [1, 2, 3, 4]
array = [1, 2]
array.append(3, 4) #=> [1, 2, 3, 4]
array #=> [1, 2, 3, 4]

14. Top-level constant look-up is no longer available
# this is removed:
irb(main):001:0> class Auth; end
=> nil
irb(main):002:0> class Twitter; end
=> nil
irb(main):003:0> Twitter::Auth
(irb):3: warning: toplevel constant Auth referenced by Twitter::Auth
=> Auth

15. Print backtrace and error message in reverse order
AFTER:
stack frame 3
stack frame 2
stack frame 1
Main Error Message
.....
BEFORE:
Main Error Message
stack frame 1
stack frame 2
stack frame 3
.....

16. Performance improvements
2

17. Performance improvements
◉ About 5-10% performance improvement by removing all
trace instructions from overall bytecode (instruction
sequences)

18. Performance improvements
◉ About 5-10% performance improvement by removing all
trace instructions from overall bytecode (instruction
sequences)
◉ Block passing by a block parameter
(e.g. def foo(&b); bar(&b); end)
is about 3 times faster than Ruby 2.4

19. Performance improvements
◉ About 5-10% performance improvement by removing all
trace instructions from overall bytecode (instruction
sequences)
◉ Block passing by a block parameter
(e.g. def foo(&b); bar(&b); end)
is about 3 times faster than Ruby 2.4
◉ ERB now generates code from a template twice as fast as
Ruby 2.4

20. Performance improvements
◉ About 5-10% performance improvement by removing all
trace instructions from overall bytecode (instruction
sequences)
◉ Block passing by a block parameter
(e.g. def foo(&b); bar(&b); end)
is about 3 times faster than Ruby 2.4
◉ ERB now generates code from a template twice as fast as
Ruby 2.4
◉ (and more…)

21. Other notable changes
3

22. Other notable changes
◉ Thread.report_on_exception is now set to true by default.

23. Other notable changes
◉ Thread.report_on_exception is now set to true by default.
◉ SecureRandom now prefers OS-provided sources over
OpenSSL

24. Other notable changes
◉ Thread.report_on_exception is now set to true by default.
◉ SecureRandom now prefers OS-provided sources over
OpenSSL
◉ Promote cmath, csv, date, dbm, etc, fcntl, fiddle, fileutils,
gdbm, ipaddr, scanf, sdbm, stringio, strscan, webrick, zlib
from standard libraries to default gems.

25. Other notable changes
◉ Thread.report_on_exception is now set to true by default.
◉ SecureRandom now prefers OS-provided sources over
OpenSSL
◉ Promote cmath, csv, date, dbm, etc, fcntl, fiddle, fileutils,
gdbm, ipaddr, scanf, sdbm, stringio, strscan, webrick, zlib
from standard libraries to default gems.
◉ Update supported Unicode version to 10.0.0.

26. Other notable changes
◉ Thread.report_on_exception is now set to true by default.
◉ SecureRandom now prefers OS-provided sources over
OpenSSL
◉ Promote cmath, csv, date, dbm, etc, fcntl, fiddle, fileutils,
gdbm, ipaddr, scanf, sdbm, stringio, strscan, webrick, zlib
from standard libraries to default gems.
◉ Update supported Unicode version to 10.0.0.
◉ Update to RubyGems 2.7.3, RDoc 6.0.1.

27. Other notable changes
◉ Thread.report_on_exception is now set to true by default.
◉ SecureRandom now prefers OS-provided sources over
OpenSSL
◉ Promote cmath, csv, date, dbm, etc, fcntl, fiddle, fileutils,
gdbm, ipaddr, scanf, sdbm, stringio, strscan, webrick, zlib
from standard libraries to default gems.
◉ Update supported Unicode version to 10.0.0.
◉ Update to RubyGems 2.7.3, RDoc 6.0.1.
◉ (and more…)

28. SUMMARY
new features
performance
improvements
other notable
changes

29. THANKS!
Live long and prosper :)
Ireneusz Skrobiś
@ireneuszskrobis