Ruby

The behavior of the splat operator as used in methods is like removing [ ] from an array to use as parameters.

eval("xaz = [1,2,3]; def biz(a,b,c) puts a, b, c; end; biz(*xaz)") # 1 # 2 # 3 # => nil 

So intuitively it would make sense that it would remove them for interpolation from a string.

zax = [1,2,3] # => [1, 2, 3]  eval("def zib(a,b,c) puts a, b, c; end; zib(#{*zax})") # SyntaxError: (irb):23: syntax error, unexpected tSTRING_DEND, expecting '=' # eval("def zib(a,b,c) puts a, b, c; end; zib(#{*zax})") # ^ # (irb):23: unterminated string meets end of file 

It seems odd to only work this way in the method argument call when it can be used the same way.

eval("def zab(a,b,c) puts a, b, c; end; zab(*#{zax})") # 1 # 2 # 3 # => nil 

It's not so much a "need" as it behaves differently than expected in my mind. When I explain the splat operator to people I say that it brakes the values out of an Array. So just thinking in this way the splat turns my_method(*[1,2,3]) into my_method(1,2,3) then it would make sense to do the same for "#{*[1,2,3]}" into "1,2,3".

On 4 March 2015 at 14:01, 6ftdan@gmail.com wrote:

Issue #10930 has been updated by Daniel P. Clark.

The behavior of the splat operator as used in methods is like removing [ ]
from and array to use as parameters.

So intuitively it would make sense that it would remove them for
interpolation from a string.

S
​o are you also requesting that "#{1, 2, 3}" be considered valid? Because
that's how I would interpret "#{*[1,2,3]}" if I saw it in code.

I'm strongly opposed to it ever arbitrarily injecting commas, especially
since Array#to_s joins without any delimiter.

--
Matthew Kerwin
http://matthew.kerwin.net.au/

Matthew Kerwin wrote:

I'm strongly opposed to it ever arbitrarily injecting commas, especially
since Array#to_s joins without any delimiter.

It doesn't actually:

2.2.0 :001 > puts %w(a b c).to_s ["a", "b", "c"] 

join joins without a comma:

2.2.0 :002 > puts %w(a b c).join abc 

Also, I agree with your point.

On 5 March 2015 at 07:04, recursive.madman@gmx.de wrote:

Issue #10930 has been updated by Recursive Madman.

Matthew Kerwin wrote:

I'm strongly opposed to it ever arbitrarily injecting commas, especially
since Array#to_s joins without any delimiter.

It doesn't actually:

2.2.0 :001 > puts %w(a b c).to_s ["a", "b", "c"] 

​Oh, wow, yeah that changed in 1.9. I must have been burned badly by 1.8 to
carry that baggage this long. :)

--
Matthew Kerwin
http://matthew.kerwin.net.au/

Matthew Kerwin wrote:

S​o are you also requesting that "#{1, 2, 3}" be considered valid? Because
that's how I would interpret "#{*[1,2,3]}" if I saw it in code.

"#{1,2,3}" # SyntaxError: (irb):1: syntax error, unexpected ',', expecting tSTRING_DEND # "#{1,2,3}" # ^ 

I see your point. Comma seperated items themselves don't currently work in interpolation. So I guess this suggestion isn't as valid as I thought it was. I was just thinking of the same behavior "as a string" and not about the step in between.

To better demonstrate the pain point here.

class Example def method_missing m, *a puts "Method #{m} called with arguments ", *a end end Example.new.foo :bar, :baz #Method foo called with arguments  #bar #baz class Example def method_missing m, *a puts "Method #{m} called with arguments #{a}" end end Example.new.foo :bar, :baz #Method foo called with arguments [:bar, :baz] 

Neither of these are the desired behavior. It ends up needing to be implemented like this.

class Example def method_missing m, *a puts "Method #{m} called with arguments #{a.to_s[1..-2]}" end end Example.new.foo :bar, :baz #Method foo called with arguments :bar, :baz 

It's not a big deal. Just an inconvenience .

class String def crop(edge=1) self[edge..-(edge+1)] end end class Array def to_str to_s.crop end end class Example def method_missing m, *a puts "Method #{m} called with arguments #{a}" end end Example.new.foo :bar, :baz #Method foo called with arguments :bar, :baz 

This ^ would make me happy :-)

Just a note... interpolation seems to call to_s and not to_str on an Array. Shouldn't to_str be the first called method on implicit conversion of an Array to a String?