Is it ok to use any to check if an array is not empty

Question

Is it bad to check if an array is not empty by using any  method   a    1 2 3   a any    gt  true  a clear  a any    gt  false   Or is it better to use unless a empty

User · Answer

Avoid any  for large arrays    any  is O n  empty  is O 1    any  does not check the length but actually scans the whole array for truthy elements   static VALUE rb ary any p VALUE ary      long i  len   RARRAY LEN ary     const VALUE  ptr   RARRAY CONST PTR ary      if   len  return Qfalse    if   rb block given p          for  i   0  i  lt  len    i  if  RTEST ptr i    return Qtrue        else       for  i   0  i  lt  RARRAY LEN ary     i            if  RTEST rb yield RARRAY AREF ary  i     return Qtrue              return Qfalse      empty  on the other hand checks the length of the array only   static VALUE rb ary empty p VALUE ary      if  RARRAY LEN ary     0      return Qtrue    return Qfalse      The difference is relevant if you have  sparse  arrays that start with lots of nil values  like for example an array that was just created

User · Answer

Prefixing the statement with an exclamation mark will let you know whether the array is not empty  So in your case -   a    1 2 3   a empty    gt  true

User · Answer

I don t think it s bad to use any  at all  I use it a lot  It s clear and concise   However if you are concerned about all nil values throwing it off  then you are really asking if the array has size  gt  0  In that case  this dead simple extension  NOT optimized  monkey-style  would get you close   Object class eval do    def size      respond to   size   amp  amp  size  gt  0   end  end   gt   foo  size     gt  true  gt     size     gt  false  gt      size     gt  true  gt     size     gt  false  gt   11 22  size     gt  true  gt   nil  size     gt  true   This is fairly descriptive  logically asking  does this object have a size    And it s concise  and it doesn t require ActiveSupport  And it s easy to build on   Some extras to think about    This is not the same as present  from ActiveSupport  You might want a custom version for String  that ignores whitespace  like present  does   You might want the name length  for String or other types where it might be more descriptive  You might want it custom for Integer and other Numeric types  so that a logical zero returns false

User · Answer

I ll suggest using unlessand blank to check is empty or not    Example     unless a blank    a    Is not empty  end   This will know  a  empty or not   If  a  is blank then the below code will not run

User · Answer

The difference between an array evaluating its values to true or if its empty  The method empty  comes from the Array class http   ruby-doc org core-2 0 0 Array html method-i-empty-3F It s used to check if the array contains something or not  This includes things that evaluate to false  such as nil and false   gt  gt  a        gt      gt  gt  a empty    gt  true  gt  gt  a    nil  false    gt   nil  false   gt  gt  a empty    gt  false  gt  gt  a    nil    gt   nil   gt  gt  a empty    gt  false   The method any  comes from the Enumerable module  http   ruby-doc org core-2 0 0 Enumerable html method-i-any-3F It s used to evaluate if  quot any quot  value in the array evaluates to true  Similar methods to this are none   all  and one   where they all just check to see how many times true could be evaluated  which has nothing to do with the count of values found in a array  case 1  gt  gt  a        gt      gt  gt  a any    gt  false  gt  gt  a one    gt  false  gt  gt  a all    gt  true  gt  gt  a none    gt  true  case 2  gt  gt  a    nil  true    gt   nil  true   gt  gt  a any    gt  true  gt  gt  a one    gt  true  gt  gt  a all    gt  false  gt  gt  a none    gt  false  case 3  gt  gt  a    true  true    gt   true  true   gt  gt  a any    gt  true  gt  gt  a one    gt  false  gt  gt  a all    gt  true  gt  gt  a none    gt  false

User · Answer

any  isn t the same as not empty  in some cases    gt  gt   nil  1  any    gt  true  gt  gt   nil  nil  any    gt  false   From the documentation      If the block is not given  Ruby adds   an implicit block of   obj  obj   that   is any  will return true if at least   one of the collection members is not   false or nil

[ruby] Is it ok to use `any?` to check if an array is not empty?

Examples related to ruby

Examples related to arrays