move check parameter for /rosout_disable_topics_generation only for initialization time

[k-okada]

PR #1241 outputs a lot of warning message with a debug log level.
c.f. #1241 (comment)

other workaround is to check hasParam before retriving a cached parameter.

diff --git a/clients/roscpp/src/libros/rosout_appender.cpp b/clients/roscpp/src/libros/rosout_appender.cpp
index f22cd9596..c7adaca73 100644
--- a/clients/roscpp/src/libros/rosout_appender.cpp
+++ b/clients/roscpp/src/libros/rosout_appender.cpp
@@ -106,7 +106,8 @@ void ROSOutAppender::log(::ros::console::Level level, const char* str, const cha
   
   // check parameter server/cache for omit_topics flag
   // the same parameter is checked in rosout.py for the same purpose
-  ros::param::getCached("/rosout_disable_topics_generation", disable_topics_);
+  if (ros::param::has("/rosout_disable_topics_generation"))
+    ros::param::getCached("/rosout_disable_topics_generation", disable_topics_);
 
   if (!disable_topics_){
     this_node::getAdvertisedTopics(msg->topics);

[dirk-thomas]

Moving the logic from the log function to the constructor changes behavior. Without the patch it is possible to set the parameter afterwards to influence the behavior at runtime. The patch removes that possibility. Therefore I think this shouldn't be applied as is.

[flixr]

While this patch changes the behavior, I would still be in favor or merging this.
It is the lesser of two evils...

[dirk-thomas]

Resolved via #1823 instead.