[gpsd-dev] [PATCH] libgpsmm: add is_open method

[spdawson]

From: Simon Dawson <address@hidden>

The gpsmm constructor effectively hides the useful status flag returned
by the underlying gps_open call.

It is extremely useful for client code to be able to check that the
gpsmm constructor was successful. To this end, add a gpsmm::is_open method
which simply checks that the gpsmm::to_user member is non-NULL. A NULL
gpsmm::to_user member can only mean that the constructor was not successful.

Signed-off-by: Simon Dawson <address@hidden>
---
 libgpsmm.cpp | 5 +++++
 libgpsmm.h   | 1 +
 2 files changed, 6 insertions(+)

diff --git a/libgpsmm.cpp b/libgpsmm.cpp
index fa421aa..2707e44 100644
--- a/libgpsmm.cpp
+++ b/libgpsmm.cpp
@@ -83,6 +83,11 @@ void gpsmm::enable_debug(int level, FILE *fp)
 #endif /* CLIENTDEBUG_ENABLE */
 }
 
+bool gpsmm::is_open(void)
+{
+       return to_user != NULL;
+}
+
 gpsmm::~gpsmm()
 {
     if ( to_user != NULL ) {
diff --git a/libgpsmm.h b/libgpsmm.h
index 2b87b89..ab656b6 100644
--- a/libgpsmm.h
+++ b/libgpsmm.h
@@ -45,6 +45,7 @@ class LIBQGPSMMSHARED_EXPORT gpsmm {
                bool waiting(int);      // blocking check for data waiting
                void clear_fix(void);
                void enable_debug(int, FILE*);
+               bool is_open(void);     // check for constructor success
        private:
                struct gps_data_t *to_user;     //we return the user a copy of 
the internal structure. This way she can modify it without
                                                //integrity loss for the entire 
class
-- 
1.8.3.2