From 7051655c766120cf523e6593c501cf8eb984adab Mon Sep 17 00:00:00 2001
From: Vladimir Prus <ghost@cs.msu.su>
Date: Sat, 8 Jan 2011 11:45:50 +0000
Subject: [PATCH] Clarify docs for 'zero_token'. Fixes #1132.

[SVN r67774]
---
 doc/overview.xml                                 |  2 +-
 include/boost/program_options/value_semantic.hpp | 10 +++++++++-
 src/cmdline.cpp                                  |  2 +-
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/doc/overview.xml b/doc/overview.xml
index 09af655..dcfbaf4 100644
--- a/doc/overview.xml
+++ b/doc/overview.xml
@@ -181,7 +181,7 @@ options_description desc;
 desc.add_options()
     ("help", "produce help message")
     ("compression", value&lt;string&gt;(), "compression level")
-    ("verbose", value&lt;string&gt;()->zero_tokens(), "verbosity level")
+    ("verbose", value&lt;string&gt;()->implicit_value("0"), "verbosity level")
     ("email", value&lt;string&gt;()->multitoken(), "email to send to")
     ;
       </programlisting>
diff --git a/include/boost/program_options/value_semantic.hpp b/include/boost/program_options/value_semantic.hpp
index 033009e..7b34bb2 100644
--- a/include/boost/program_options/value_semantic.hpp
+++ b/include/boost/program_options/value_semantic.hpp
@@ -261,13 +261,21 @@ namespace boost { namespace program_options {
             return this;
         }
 
-        /** Specifies that the value can span multiple tokens. */
+        /** Specifies that the value can span multiple tokens. 
+        */
         typed_value* multitoken()
         {
             m_multitoken = true;
             return this;
         }
 
+        /** Specifies that no tokens may be provided as the value of
+            this option, which means that only presense of the option
+            is significant. For such option to be useful, either the
+            'validate' function should be specialized, or the 
+            'implicit_value' method should be also used. In most
+            cases, you can use the 'bool_switch' function instead of
+            using this method. */
         typed_value* zero_tokens() 
         {
             m_zero_tokens = true;
diff --git a/src/cmdline.cpp b/src/cmdline.cpp
index be31385..09e0256 100644
--- a/src/cmdline.cpp
+++ b/src/cmdline.cpp
@@ -277,7 +277,7 @@ namespace boost { namespace program_options { namespace detail {
         }
 
         /* If an key option is followed by a positional option,
-           can can consume more tokens (e.g. it's multitoke option),
+           can can consume more tokens (e.g. it's multitoken option),
            give those tokens to it.  */
         vector<option> result2;
         for (unsigned i = 0; i < result.size(); ++i)