close-stream: new : protocol from close method.

* stream.c (close_stream): If the underlying method
returns the colon symbol :, then keep the cached
close_result as nil, so that the method can be called
again, but return t to the caller to indicate success.

* tests/018/close-delegate.tl: Test case added.

* tests/018/close-delegate.expected: Updated.

* txr.1: Documented.

2 files changed, 24 insertions, 1 deletions

diff --git a/tests/018/close-delegate.expected b/tests/018/close-delegate.expected
index 227f9f67..de68447f 100644
--- a/tests/018/close-delegate.expected
+++ b/tests/018/close-delegate.expected
@@ -1,3 +1,6 @@
 close called, count 2
 close called, count 1
-20
+40
+close called, count 2
+close called, count 1
+40
diff --git a/tests/018/close-delegate.tl b/tests/018/close-delegate.tl
index 4cf1d650..64a1dc91 100644
--- a/tests/018/close-delegate.tl
+++ b/tests/018/close-delegate.tl
@@ -18,3 +18,23 @@
     (get-lines s))
   len
   prinl)
+
+(defstruct refcount-close-alt stream-wrap
+  stream
+  (count 1)
+
+  (:method close (me throw-on-error-p)
+    (put-line `close called, count @{me.count}`)
+    (when (plusp me.count)
+      (if (zerop (dec me.count))
+        (close-stream me.stream throw-on-error-p)
+        :))))
+
+(flow
+  (with-stream (s (make-struct-delegate-stream
+                    (new refcount-close-alt
+                         count 2
+                         stream (open-file *load-path*))))
+    (get-lines s))
+  len
+  prinl)