add {Array|Hash|String}.try_convert

1 files changed, 35 insertions, 0 deletions

diff --git a/mrbgems/mruby-array-ext/mrblib/array.rb b/mrbgems/mruby-array-ext/mrblib/array.rb
index 35be79339..f19581cdc 100644
--- a/mrbgems/mruby-array-ext/mrblib/array.rb
+++ b/mrbgems/mruby-array-ext/mrblib/array.rb
@@ -1,6 +1,31 @@
 class Array
   ##
   # call-seq:
+  #    Array.try_convert(obj) -> array or nil
+  #
+  # Tries to convert +obj+ into an array, using +to_ary+ method.
+  # converted array or +nil+ if +obj+ cannot be converted for any reason.
+  # This method can be used to check if an argument is an array.
+  #
+  #    Array.try_convert([1])   #=> [1]
+  #    Array.try_convert("1")   #=> nil
+  #
+  #    if tmp = Array.try_convert(arg)
+  #      # the argument is an array
+  #    elsif tmp = String.try_convert(arg)
+  #      # the argument is a string
+  #    end
+  #
+  def self.try_convert(obj)
+    if obj.respond_to?(:to_ary)
+      obj.to_ary
+    else
+      nil
+    end
+  end
+
+  ##
+  # call-seq:
   #    ary.uniq!                -> ary or nil
   #    ary.uniq! { |item| ... } -> ary or nil
   #
@@ -709,4 +734,14 @@ class Array
     end
     nil
   end
+
+  ##
+  #  call-seq:
+  #     ary.to_ary -> ary
+  #
+  #  Returns +self+.
+  #
+  def to_ary
+    self
+  end
 end