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-rw-r--r--enum.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/enum.c b/enum.c
index 157b615..56d304c 100644
--- a/enum.c
+++ b/enum.c
@@ -3668,6 +3668,32 @@ enum_sum_iter_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, args))
/*
+ * call-seq:
+ * enum.sum(init=0) -> number
+ * enum.sum(init=0) {|e| expr } -> number
+ *
+ * Returns the sum of elements in an Enumerable.
+ *
+ * If a block is given, the block is applied to each element
+ * before addition.
+ *
+ * If <i>enum</i> is empty, it returns <i>init</i>.
+ *
+ * For example:
+ *
+ * { 1 => 10, 2 => 20 }.sum {|k, v| k * v } #=> 50
+ * (1..10).sum #=> 55
+ * (1..10).sum {|v| v * 2 } #=> 110
+ * [Object.new].each.sum #=> TypeError
+ *
+ * This method can be used for non-numeric objects by
+ * explicit <i>init</i> argument.
+ *
+ * { 1 => 10, 2 => 20 }.sum([]) #=> [1, 10, 2, 20]
+ * "a\nb\nc".each_line.lazy.map(&:chomp).sum("") #=> "abc"
+ *
+ * Enumerable#sum method may not respect method redefinition of "+"
+ * methods such as Integer#+.
*/
static VALUE
enum_sum(int argc, VALUE* argv, VALUE obj)