Ruby 2.5 includes new features such as allowing rescue/else/ensure blocks directly in do/end, yield_self, Hash slicing methods, and Struct classes that accept keyword arguments. It also provides performance improvements like removing trace instructions for 5-10% faster execution and optimizing block passing. Additionally, there are other notable changes like Thread exceptions defaulting to report, SecureRandom preferring OS sources, and updates to standard libraries, Unicode version, RubyGems, and RDoc.

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