问题
I don't understand why my method translate
undefines start_with?
method and is messing something in irb, so I can exit irb only by pressing Ctrl+d, not exit
or quit
:
>> "hello".respond_to?(:start_with?)
=> true
>> def translate(string)
>> if string.start_with?("a", "e", "i", "o", "u")
>> string += "ay"
>> end
>> end
NoMethodError: undefined method `start_with?' for #<RubyVM::InstructionSequence:0x00000001d4c960>
from (irb):3:in `translate'
from /usr/local/rvm/rubies/ruby-2.3.0/bin/irb:11:in `<main>'
>> "hello".respond_to?(:start_with?)
NoMethodError: undefined method `start_with?' for <RubyVM::InstructionSequence:irb_binding@(irb)>:RubyVM::InstructionSequence
from (irb):3:in `translate'
from /usr/local/rvm/rubies/ruby-2.3.0/bin/irb:11:in `<main>'
>> exit
NoMethodError: undefined method `start_with?' for <RubyVM::InstructionSequence:irb_binding@(irb)>:RubyVM::InstructionSequence
from (irb):3:in `translate'
from /usr/local/rvm/rubies/ruby-2.3.0/bin/irb:11:in `<main>'
>> quit
NoMethodError: undefined method `start_with?' for <RubyVM::InstructionSequence:irb_binding@(irb)>:RubyVM::InstructionSequence
from (irb):3:in `translate'
from /usr/local/rvm/rubies/ruby-2.3.0/bin/irb:11:in `<main>'
>>
I tried two different workspaces and effect is the same.
My Ruby and Rails versions are:
~/workspace $ ruby -v
ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-linux]
~/workspace $ rails -v
Rails 4.2.2
from my other question I know that word translate
is used by many I18N libraries, so it's my only suspect, hence the title of this question. However as a beginner, I don't see any relation.
回答1:
It is a bug in YARV that was fixed in YARV 2.4.0.
The commit message mentions the following workaround if you don't have YARV 2.4.0:
class << RubyVM::InstructionSequence def translate; end undef translate end
Note that other implementations are not affected, only YARV.
回答2:
Here is a theory
- There is probably a global function
translate
in your setup - This function is called with an instruction sequence as argument when
irb
prints the output - Hence when you redefine
translate
printing the output breaks
The NoMethodError: undefined method
does not mean that the method has been undefined globally but that it is being sent to an object that does not understand it
You can test my theory by executing
method(:translate)
If you get a result back then translate
is already defined and your must not redefine it!
Now if you want to know which gem defined this function, install pry
gem (which is a better irb) and use the $
command to look at the file and source code of that method
# Use this command in pry to see location and source code
$ translate
来源:https://stackoverflow.com/questions/41590976/why-word-translate-is-messing-irb