Clever Geek Handbook

Is this valid ruby ​​syntax?

if step.include? "apples" or "banana" or "cheese"
say "yay"
end
+2


source to share


8 answers


Several problems with your code.

step.include? "apples" or "banana" or "cheese"

This expression evaluates to:

step.include?("apples") or ("banana") or ("cheese")

Since Ruby treats all values ​​other than false

and nil

as true, this expression will always be true. (In this case, the value "banana"

will be a short-circuit expression and cause it to evaluate to true, even if the step value contains none of these three.)

Your intention:

step.include? "apples" or step.include? "banana" or step.include? "cheese"

However, this is ineffective. Also it uses or

instead ||

, which has a different operator precedence and shouldn't normally be used in conditional expressions if

.



Common or

usage:

do_something or raise "Something went wrong."

The best way to write this would be this:

step =~ /apples|banana|cheese/

It uses the regular expression you are going to use in Ruby.

Finally, there is no method in Ruby say

unless you define one. Usually you print something by calling puts

.

So the final code looks like this:

if step =~ /apples|banana|cheese/
  puts "yay"
end
+6


source


The last two expressions appear to Ruby to be true and have nothing to do with the phrase include?

.

Assuming which step

is a string ...

step = "some long string with cheese in the middle"


you could write something like this.

puts "yay" if step.match(/apples|banana|cheese/)
+3


source


Here, you can call step.include?

for each of the arguments until one of them returns true

:

if ["apples", "banana", "cheese"].any? {|x| step.include? x}
+2


source


This is definitely not what you think you want. The method include?

takes on a value String

that is not what it creates "apples" or "banana" or "cheese"

. Try this instead:

puts "yay" if ["apples", "banana", "cheese"].include?(step)

But it is not clear from the context which step should be. If it's just one word, then it's okay. If it could be a whole sentence, try joel.neely's answer.

+1


source


The closest thing to a syntax that will do what you think you want is something like this:

  if ["apples", "banana", "cheese"].include?(step)
    puts "yay"
  end

But one of the other suggestions using regex would be more concise and readable.

+1


source


Assuming that step

is Array

or Set

or something else that supports the given operator intersection &

, I think the following code is the most idiomatic:

unless (step & ["apples","banana","cheese"]).empty?
  puts 'yay'
end
+1


source


I'll add some parentheses for you:

if (step.include? "apples") or ("banana") or ("cheese")
    say "yay"
end

(This is why he always says "yay" - because the expression will always be true.)

0


source


Just add one more side ...

If it step

is Array

(as the call seems to suggest include?

), perhaps the code should be:

if (step - %w{apples banana cheese}) != step
  puts 'yay'
end
-1


source






More articles:


All Articles