Ruby - test for array

Question

What is the right way to   is array  something       gt  false          or 1   is array   something    else        gt  true   or  gt  1    or to get the count of items in it

User · Accepted Answer

You probably want to use kind of      gt  gt  s    something    gt   something   gt  gt  s kind of  Array    gt  false  gt  gt  s     something    else     gt    something    else    gt  gt  s kind of  Array    gt  true

User · Answer

1 2 3  is a  Array evaluates to true

User · Answer

It sounds like you re after something that has some concept of items  I d thus recommend seeing if it is Enumerable  That also guarantees the existence of  count   For example    1 2 3  is a  Enumerable  1 2 3  count   note that  while size  length and count all work for arrays  count is the right meaning here -  for example   abc  length and  abc  size both work  but  abc  count doesn t work like that    Caution  a string is a  Enumerable  so perhaps this isn t what you want    depends on your concept of an array like object

User · Answer

Are you sure it needs to be an array  You may be able to use respond to  method  so your code would work for similar things that aren t necessarily arrays  maybe some other enumberable thing   If you do actually need an array  then the post describing the Array kind  of  method is best     hello   respond to   each

User · Answer

Instead of testing for an Array  just convert whatever you get into a one-level Array  so your code only needs to handle the one case   t     something        or    t   Array something    or    def f  x         end   Ruby has various ways to harmonize an API which can take an object or an Array of objects  so  taking a guess at why you want to know if something is an Array  I have a suggestion   The splat operator contains lots of magic you can look up  or you can just call Array something  which will add an Array wrapper if needed  It s similar to   something  in this one case   def f x   p Array x  inspect   p   x  inspect end f 1             gt    1   f  1            gt    1   f  1 2          gt    1  2     Or  you could use the splat in the parameter declaration and then  flatten  giving you a different sort of collector   For that matter  you could call  flatten above  too    def f  x   p x flatten inspect end             gt  nil f 1             gt    1   f 1 2           gt    1  2   f  1            gt    1   f  1 2          gt    1  2   f  1 2  3 4     gt    1  2  3  4     And  thanks gregschlom  it s sometimes faster to just use Array x  because when it s already an Array it doesn t need to create a new object

User · Answer

Try   def is array a      a class    Array end   EDIT  The other answer is much better than mine

User · Answer

Also consider using Array    From the Ruby Community Style Guide      Use Array   instead of explicit Array check or   var   when dealing   with a variable you want to treat as an Array  but you re not certain   it s an array      bad paths    paths  unless paths is a  Array paths each    path  do something path       bad  always creates a new Array instance    paths  each    path  do something path       good  and a bit more readable  Array paths  each    path  do something path

[ruby] Ruby - test for array

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