新版包括了一系列新的特性和性能改进。主要变化包括：rescue/else/ensure 允许直接与 do/end 块使用，yield 增加 yield_self，Struct.new 能创建接受关键字参数的类，最高级常量查询不再可用，移除所有 trace 指令提升 5-10% 性能，SecureRandom 将更偏向使用操作系统提供的 SSL 库
rescue/else/ensure 允许直接与 do/end 块使用。?[Feature #12906]
yield 增加 yield_self。?[Feature #6721]
支持分行覆盖范围和方法覆盖率测量。The branch coverage indicates which branches are executed and which are not. The method coverage indicates which methods are invoked and which are not. By running the test suite with these new features, you will know which branches and methods are executed, and evaluate total coverage of the test suite more strictly.?[Feature #13901]
Struct.new 能创建接受关键字参数的类。?[Feature #11925]
枚举 #any?,all?,none? and one? 接收模式参数?[Feature #11286]
pp.rb 现在自动加载。?[Feature #14123]
Print backtrace and error message in reverse order (oldest call first, most recent call last). When a long backtrace appears on your terminal (TTY), you can easily find the cause line at the bottom of the backtrace. Note that the order is reversed only when backtrace is printed out to the terminal directly.?[Feature #8661]?[experimental]
About 5-10% performance improvement by removing all?trace?instructions from overall bytecode (instruction sequences).The?trace?instruction was added to support the?TracePoint. However, in most cases,?TracePoint?is not used and?trace?instructions are pure overhead. Instead, now we use a dynamic instrumentation technique. See?[Feature #14104]?for more details.
Block passing by a block parameter (e.g.?def foo(&b); bar(&b); end) is about 3 times faster than Ruby 2.4 by “Lazy Proc allocation” technique.?[Feature #14045]
Mutex is rewritten to be smaller and faster.?[Feature #13517]
ERB now generates code from a template which runs twice as fast as Ruby 2.4.
Improve performance of some built-in methods including?Array#concat,?Enumerable#sort_by,?String#concat,?String#index,?Time#+?and more.
IO.copy_stream uses copy_file_range(2) to copy offload?[Feature #13867]
SecureRandom now prefers OS-provided sources over OpenSSL.?[Bug #9569]
Promote cmath, csv, date, dbm, etc, fcntl, fiddle, fileutils, gdbm, ipaddr, scanf, sdbm, stringio, strscan, webrick, zlib from standard libraries to default gems.
Update to Psych 3.0.2.
Update to RubyGems 2.7.3.
Update to RDoc 6.0.1.
Fix a significant amount of bugs that existed over ten years.
Add support for new Ruby syntax from the latest versions.
Update supported Unicode version to 10.0.0.
Thread.report_on_exception?is now set to true by default. This change helps debugging of multi-threaded programs.?[Feature #14143]
IO#write now receives multiple arguments?[Feature #9323]