GCS_MAVLink: code-generate chan-fetching methods

A recent PR had to change every single one of these methods, which was kind of unfortunate. So generate the methods using a #define so the duplication happens at preprocessor-time.
tridge · Dec 14, 2022 · 4e61de7 · 4e61de7
1 parent d9dedf3
commit 4e61de7
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Showing 2 changed files with 28 additions and 14 deletions.
diff --git a/libraries/GCS_MAVLink/GCS.h b/libraries/GCS_MAVLink/GCS.h
@@ -86,6 +86,28 @@ void gcs_out_of_space_to_send(mavlink_channel_t chan);
     }
 #define MAV_STREAM_TERMINATOR { (streams)0, nullptr, 0 }
 
+// code generation; avoid each subclass duplicating these two methods
+// and just changing the name.  These methods allow retrieval of
+// objects specific to the vehicle's subclass, which the vehicle can
+// then call its own specific methods on
+#define GCS_MAVLINK_CHAN_METHOD_DEFINITIONS(subclass_name) \
+    subclass_name *chan(const uint8_t ofs) override {                   \
+        if (ofs > _num_gcs) {                                           \
+            INTERNAL_ERROR(AP_InternalError::error_t::gcs_offset);      \
+            return nullptr;                                             \
+        }                                                               \
+        return (subclass_name *)_chan[ofs];                        \
+    }                                                                   \
+                                                                        \
+    const subclass_name *chan(const uint8_t ofs) const override { \
+        if (ofs > _num_gcs) {                                           \
+            INTERNAL_ERROR(AP_InternalError::error_t::gcs_offset);      \
+            return nullptr;                                             \
+        }                                                               \
+        return (subclass_name *)_chan[ofs];                        \
+    }
+
+
 #define GCS_MAVLINK_NUM_STREAM_RATES 10
 class GCS_MAVLINK_Parameters
 {

diff --git a/libraries/GCS_MAVLink/GCS_Dummy.h b/libraries/GCS_MAVLink/GCS_Dummy.h
@@ -61,20 +61,12 @@ class GCS_Dummy : public GCS
     }
 
 private:
-    GCS_MAVLINK_Dummy *chan(const uint8_t ofs) override {
-        if (ofs > _num_gcs) {
-            INTERNAL_ERROR(AP_InternalError::error_t::gcs_offset);
-            return nullptr;
-        }
-        return (GCS_MAVLINK_Dummy *)_chan[ofs];
-    };
-    const GCS_MAVLINK_Dummy *chan(const uint8_t ofs) const override {
-        if (ofs > _num_gcs) {
-            INTERNAL_ERROR(AP_InternalError::error_t::gcs_offset);
-            return nullptr;
-        }
-        return (GCS_MAVLINK_Dummy *)_chan[ofs];
-    };
+    // the following define expands to a pair of methods to retrieve a
+    // pointer to an object of the correct subclass for the link at
+    // offset ofs.  These are of the form:
+    // GCS_MAVLINK_XXXX *chan(const uint8_t ofs) override;
+    // const GCS_MAVLINK_XXXX *chan(const uint8_t ofs) override const;
+    GCS_MAVLINK_CHAN_METHOD_DEFINITIONS(GCS_MAVLINK_Dummy);
 
     void send_textv(MAV_SEVERITY severity, const char *fmt, va_list arg_list, uint8_t dest_bitmask) override;