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Feature #16295

Updated by Dan0042 (Daniel DeLorme) over 2 years ago

Original discussion https://bugs.ruby-lang.org/issues/16150?next_issue_id=16147&prev_issue_id=16153#note-40 

 In #16150, @headius raised the following concern about `String#-@` and `String#+@`: 

 headius (Charles Nutter) wrote: 
 > > Not exactly, -@ and +@ makes this much simpler 
 >  
 > I do like the unary operators, but they also have some precedence oddities: 
 >  
 > ``` 
 > >> -"foo".size 
 > => -3 
 > >> (-"foo").size 
 > => 3 
 > ``` 
 >  
 > And it doesn't work at all if you're chaining method calls: 
 >  
 > ``` 
 > >> +ary.to_s.frozen? 
 > NoMethodError: undefined method `+@' for false:FalseClass 
 >  	 from (irb):8 
 >  	 from /usr/bin/irb:11:in `<main>' 
 > ``` 
 >  
 > But you are right, instead of the explicit `dup` with possible freeze you could use `-` or `+` on the result of `to_s`. However it's still not safe to modify it since it would modify the original string too. 

 After working for quite a while with those, I have to say I agree. They very often force to use parentheses, which is annoying, and an indication that regular methods would be preferable to unary operators. 


 In response @matz proposed to alias them as `String#+` and `String#-` without arguments: 

 >    How about making String#+ and #- without argument behave like #+@ and #-@ respectively, so that we can write: 
 >   
 >    ``` 
 >    "foo".-.size 
 >    ary.to_s.+.frozen? ary.+.to_s.frozen? 
 >    ``` 


 My personal opinion is that descriptive method names would be preferable to `+/-`: 

 > IMHO `.-` and `.+` is not very elegant. Proper method names explaining the intent would be preferable. 
 >  
 >     - `-@` could be `dedup`, or `deduplicate`. 
 >     - `+@` could be `mutable` or `mut`. 

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