比较以下场景(它们是相同的,但结果是不同的)：
~> irb
irb(main):001:0> begin
irb(main):002:1* begin
irb(main):003:2* puts 1
irb(main):004:2> next
irb(main):005:2> end
irb(main):006:1> puts 2
irb(main):007:1> end
SyntaxError: (irb):4: Can't escape from eval with next
jruby现在一样：
~> jirb
irb(main):001:0> begin
irb(main):002:1* begin
irb(main):003:2* puts 1
irb(main):004:2> next
irb(main):005:2> end
irb(main):006:1> puts 2
irb(main):007:1> end
1
=> nil
为什么这不会像在cruby上那样在jruby上失败？这是一个犹豫不决的虫子吗？
最佳答案 我把它归档为
Bug #13064.
我在各种版本的YARV以及JRuby,MRuby和Rubinius的最新版本中测试了您的代码：
> YARV 2.2.0(使用macOS构建运输)
# ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.0.0p648 (2015-12-16 revision 53162) [universal.x86_64-darwin16]
-e:1: warning: statement not reached
-e:1: Invalid next
-e: compile error (SyntaxError)
# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.0.0"
=> "2.0.0"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/irb/workspace.rb:86 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/irb/workspace.rb:86 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
from (irb)
irb(main):011:0>
irb(main):012:0* exit
> YARV 2.3.1(JRuby声称此版本兼容)
# ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)
# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.3.1"
=> "2.3.1"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
from (irb)
irb(main):011:0>
irb(main):012:0* exit
> YARV 2.3.3
# ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)
# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.3.3"
=> "2.3.3"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.3/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.3/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.3/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
from (irb)
irb(main):011:0>
irb(main):012:0* exit
> YARV 2.4.0-preview3：
# ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.4.0preview3 (2016-11-07 trunk 56661) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)
# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.4.0"
=> "2.4.0"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.4.0-preview3/lib/ruby/2.4.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
from (irb)
irb(main):011:0>
irb(main):012:0* exit
> YARV 2.4.0-dev(截至昨天的当前SVN中继)：
# ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.4.0dev (2016-12-22 trunk 57151) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)
# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.4.0"
=> "2.4.0"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.4.0-dev/lib/ruby/2.4.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
from (irb)
irb(main):011:0>
irb(main):012:0* exit
> Rubinius 3.69
# rbx -v -W -e 'begin; begin puts 1; next end; puts 2 end'
rubinius 3.69 (2.3.1 a57071c6 2016-11-17 3.8.1) [x86_64-darwin15.6.0]
1
main # Rubinius::Loader at core/loader.rb:860
evals # Rubinius::Loader at core/loader.rb:646
eval # Kernel(Rubinius::Loader) at core/kernel.rb:1130
call_on_instance # Rubinius::BlockEnvironment at core/block_environment.rb:147
{ } in __script__ # Object at -e:1
jump_error . Rubinius at core/rubinius.rb:279
invalid context for 'next' (LocalJumpError)
An exception occurred evaluating command line code
# irb
irb(main):001:0> p RUBY_VERSION
"2.3.1"
=> "2.3.1"
irb(main):002:0> p RUBY_ENGINE
"rbx"
=> "rbx"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
1
LocalJumpError: invalid context for 'next'
from core/rubinius.rb:279:in `jump_error'
from (irb):7
from core/block_environment.rb:147:in `call_on_instance'
from core/kernel.rb:1130:in `eval'
from core/kernel.rb:585:in `loop'
from core/proc.rb:20:in `call'
from core/kernel.rb:1067:in `catch'
from core/throw_catch.rb:8:in `register'
from core/kernel.rb:1066:in `catch'
from core/proc.rb:20:in `call'
from core/kernel.rb:1067:in `catch'
from core/throw_catch.rb:8:in `register'
from core/kernel.rb:1066:in `catch'
from core/code_loader.rb:505:in `load_script'
from core/code_loader.rb:590:in `load_script'
from core/loader.rb:679:in `script'
from core/loader.rb:861:in `main'irb(main):011:0>
irb(main):012:0* exit
> JRuby 9.1.6.0(最新版本)
# jruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
jruby 9.1.6.0 (2.3.1) 2016-11-09 0150a76 Java HotSpot(TM) 64-Bit Server VM 25.102-b14 on 1.8.0_102-b14 +jit [darwin-x86_64]
1
LocalJumpError: unexpected next
<main> at -e:1
# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.3.1"
=> "2.3.1"
irb(main):002:0> p RUBY_ENGINE
"jruby"
=> "jruby"
irb(main):003:0>
irb(main):004:0* begin
irb(main):005:1* begin
irb(main):006:2* puts 1
irb(main):007:2> next
irb(main):008:2> end
irb(main):009:1> puts 2
irb(main):010:1> end
1
=> nil
irb(main):011:0>
irb(main):012:0* exit
> MRuby 1.2.0(由matz自己编写的最低ISO兼容Ruby实现)
# mruby -v -e 'begin; begin puts 1; next end; puts 2 end'
mruby 1.2.0 (2015-11-17)
00001 NODE_SCOPE:
00001 NODE_BEGIN:
00001 NODE_BEGIN:
00001 NODE_BEGIN:
00001 NODE_CALL:
00001 NODE_SELF
00001 method='puts' (383)
00001 args:
00001 NODE_INT 1 base 10
00001 NODE_NEXT:
00001 NODE_CALL:
00001 NODE_SELF
00001 method='puts' (383)
00001 args:
00001 NODE_INT 2 base 10
irep 0x7fe0e3c1b630 nregs=4 nlocals=1 pools=1 syms=1 reps=0
file: -e
1 000 OP_LOADSELF R1
1 001 OP_LOADI R2 1
1 002 OP_SEND R1 :puts 1
1 003 OP_ERR "unexpected next"
1 004 OP_LOADSELF R1
1 005 OP_LOADI R2 2
1 006 OP_SEND R1 :puts 1
1 007 OP_STOP
1
trace:
[0] -e:1
LocalJumpError: unexpected next
# irb -v
mruby 1.2.0 (2015-11-17)
mirb - Embeddable Interactive Ruby Shell
> p RUBY_VERSION
00001 NODE_SCOPE:
00001 NODE_BEGIN:
00001 NODE_CALL:
00001 NODE_SELF
00001 method='p' (384)
00001 args:
00001 NODE_CONST RUBY_VERSION
irep 0x7fceeac05220 nregs=4 nlocals=1 pools=0 syms=2 reps=0
file: (mirb)
1 000 OP_LOADSELF R1
1 001 OP_GETCONST R2 :RUBY_VERSION
1 002 OP_SEND R1 :p 1
1 003 OP_STOP
"1.9"
=> "1.9"
> p RUBY_ENGINE
00002 NODE_SCOPE:
00002 NODE_BEGIN:
00002 NODE_CALL:
00002 NODE_SELF
00002 method='p' (384)
00002 args:
00002 NODE_CONST RUBY_ENGINE
irep 0x7fceeae05cf0 nregs=4 nlocals=1 pools=0 syms=2 reps=0
file: (mirb)
2 000 OP_LOADSELF R1
2 001 OP_GETCONST R2 :RUBY_ENGINE
2 002 OP_SEND R1 :p 1
2 003 OP_STOP
"mruby"
=> "mruby"
>
00004 NODE_SCOPE:
00004 NODE_BEGIN:
irep 0x7fceeac06a50 nregs=2 nlocals=1 pools=0 syms=0 reps=0
file: (mirb)
4 000 OP_LOADNIL R1
4 001 OP_STOP
=> nil
> begin
00005 NODE_NIL
* begin
00007 NODE_NIL
* puts 1
00009 NODE_NIL
* next
00011 NODE_NIL
* end
00013 NODE_NIL
* puts 2
00015 NODE_NIL
* end
00012 NODE_SCOPE:
00012 NODE_BEGIN:
00012 NODE_BEGIN:
00012 NODE_BEGIN:
00012 NODE_CALL:
00012 NODE_SELF
00012 method='puts' (383)
00012 args:
00012 NODE_INT 1 base 10
00013 NODE_NEXT:
00015 NODE_CALL:
00015 NODE_SELF
00015 method='puts' (383)
00015 args:
00015 NODE_INT 2 base 10
irep 0x7fceeae01130 nregs=4 nlocals=1 pools=1 syms=1 reps=0
file: (mirb)
12 000 OP_LOADSELF R1
12 001 OP_LOADI R2 1
12 002 OP_SEND R1 :puts 1
13 003 OP_ERR "unexpected next"
15 004 OP_LOADSELF R1
15 005 OP_LOADI R2 2
15 006 OP_SEND R1 :puts 1
15 007 OP_STOP
1
LocalJumpError: unexpected next
>
00012 NODE_SCOPE:
00012 NODE_BEGIN:
irep 0x7fceeae078f0 nregs=2 nlocals=1 pools=0 syms=0 reps=0
file: (mirb)
12 000 OP_LOADNIL R1
12 001 OP_STOP
=> nil
> exit
最有趣的是,MRuby,JRuby和Rubinius实际上都同意这种行为,但与YARV不同. YARV或其他所有都是错的.不过,我不能说出哪些.
