Ruby concatenate strings and add spaces

问题

I have 4 string variables name, quest, favorite_color, speed that might be empty. I want to concatenate them all together, putting spaces between those that aren't empty. Simplicity of the code, i.e how simple is to to look at and understand, is more important than speed.

So:

name = 'Tim'
quest = 'destroy'
favorite_color = 'red'
speed = 'fast'

becomes

'Tim destroy red fast'

and

name = 'Steve'
quest = ''
favorite_color = ''
speed = 'slow'

becomes:

'Steve slow'

Note there is only 1 space between 'Steve' and 'slow'.

How do I do that (preferably in 1 line)?

回答1:

[name, quest, favorite_color, speed].reject(&:empty?).join(' ')

回答2:

Try [name,quest,favorite_color,speed].join(' ').squeeze(' ')

回答3:

You can use inject:

[name,quest,favorite_color,speed].inject("") {|k,v| v.empty? ? k : k << " " << v }.strip

来源：https://stackoverflow.com/questions/2434885/ruby-concatenate-strings-and-add-spaces