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authorakr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2014-10-10 09:42:47 +0000
committerakr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2014-10-10 09:42:47 +0000
commit5a77a4e71b3de4936015a0ffe4c1e92cd40caa68 (patch)
treec9f31a5bf4b6b43f0e8b3c8cbd02efe529f1ea5e /enum.c
parentb44c47d102763fbac164810884e3adcac64ef8ce (diff)
Update doc. and warnings.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47864 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'enum.c')
-rw-r--r--enum.c57
1 files changed, 29 insertions, 28 deletions
diff --git a/enum.c b/enum.c
index bea3c5b..3e25321 100644
--- a/enum.c
+++ b/enum.c
@@ -2835,12 +2835,6 @@ chunk_i(RB_BLOCK_CALL_FUNC_ARGLIST(yielder, enumerator))
* }
* }
*
- * If the block needs to maintain state over multiple elements,
- * an +initial_state+ argument can be used.
- * If a non-nil value is given,
- * a reference to it is passed as the 2nd argument of the block for the
- * +chunk+ method, so state-changes to it persist across block calls.
- *
*/
static VALUE
enum_chunk(int argc, VALUE *argv, VALUE enumerable)
@@ -2853,7 +2847,7 @@ enum_chunk(int argc, VALUE *argv, VALUE enumerable)
rb_raise(rb_eArgError, "no block given");
n = rb_scan_args(argc, argv, "01", &initial_state);
if (n != 0)
- rb_warn("initial_state given for chunk. (Use Enumerator.new with lexical scope variables.)");
+ rb_warn("initial_state given for chunk. (Use local variables.)");
enumerator = rb_obj_alloc(rb_cEnumerator);
rb_ivar_set(enumerator, rb_intern("chunk_enumerable"), enumerable);
@@ -2946,7 +2940,6 @@ slicebefore_i(RB_BLOCK_CALL_FUNC_ARGLIST(yielder, enumerator))
*
* enum.slice_before(pattern).each { |ary| ... }
* enum.slice_before { |elt| bool }.each { |ary| ... }
- * enum.slice_before(initial_state) { |elt, state| bool }.each { |ary| ... }
*
* Other methods of the Enumerator class and Enumerable module,
* such as map, etc., are also usable.
@@ -2992,33 +2985,34 @@ slicebefore_i(RB_BLOCK_CALL_FUNC_ARGLIST(yielder, enumerator))
* }.join(",")
* #=> "0,2-4,6,7,9"
*
- * However local variables are not appropriate to maintain state
- * if the result enumerator is used twice or more.
- * In such a case, the last state of the 1st +each+ is used in the 2nd +each+.
- * The _initial_state_ argument can be used to avoid this problem.
- * If non-nil value is given as _initial_state_,
- * it is duplicated for each +each+ method invocation of the enumerator.
- * The duplicated object is passed to 2nd argument of the block for
- * +slice_before+ method.
+ * However local variables should be used carefully
+ * if the result enumerator is enumerated twice or more.
+ * The local variables should be initialized for each enumeration.
+ * Enumerator.new can be used to do it.
*
* # Word wrapping. This assumes all characters have same width.
* def wordwrap(words, maxwidth)
- * # if cols is a local variable, 2nd "each" may start with non-zero cols.
- * words.slice_before(cols: 0) { |w, h|
- * h[:cols] += 1 if h[:cols] != 0
- * h[:cols] += w.length
- * if maxwidth < h[:cols]
- * h[:cols] = w.length
- * true
- * else
- * false
- * end
+ * Enumerator.new {|y|
+ * # cols is initialized in Enumerator.new.
+ * cols = 0
+ * words.slice_before { |w|
+ * cols += 1 if cols != 0
+ * cols += w.length
+ * if maxwidth < cols
+ * cols = w.length
+ * true
+ * else
+ * false
+ * end
+ * }.each {|ws| y.yield ws }
* }
* end
* text = (1..20).to_a.join(" ")
* enum = wordwrap(text.split(/\s+/), 10)
* puts "-"*10
- * enum.each { |ws| puts ws.join(" ") }
+ * enum.each { |ws| puts ws.join(" ") } # first enumeration.
+ * puts "-"*10
+ * enum.each { |ws| puts ws.join(" ") } # second enumeration generates same result as the first.
* puts "-"*10
* #=> ----------
* # 1 2 3 4 5
@@ -3028,6 +3022,13 @@ slicebefore_i(RB_BLOCK_CALL_FUNC_ARGLIST(yielder, enumerator))
* # 17 18 19
* # 20
* # ----------
+ * # 1 2 3 4 5
+ * # 6 7 8 9 10
+ * # 11 12 13
+ * # 14 15 16
+ * # 17 18 19
+ * # 20
+ * # ----------
*
* mbox contains series of mails which start with Unix From line.
* So each mail can be extracted by slice before Unix From line.
@@ -3072,7 +3073,7 @@ enum_slice_before(int argc, VALUE *argv, VALUE enumerable)
int n;
n = rb_scan_args(argc, argv, "01", &initial_state);
if (n != 0)
- rb_warn("initial_state given for slice_before. (Use Enumerator.new with lexical scope variables.)");
+ rb_warn("initial_state given for slice_before. (Use local variables.)");
enumerator = rb_obj_alloc(rb_cEnumerator);
rb_ivar_set(enumerator, rb_intern("slicebefore_sep_pred"), rb_block_proc());
rb_ivar_set(enumerator, rb_intern("slicebefore_initial_state"), initial_state);