Logging: Document how to log from multiple sources
@@ -72,6 +72,17 @@ If you want to only log messages below a specific directory prefix, then please
#endif
```
+ . To log messages from multiple source you can use the operator `&&` to chain multiple calls to `strncmp`. For example, to log messages
+ from the `directoryvalue` and `yamlcpp` plugin use the code:
+
+ ```c
+ #ifndef NO_FILTER
+ if (strncmp (file, "src/plugins/directoryvalue/", sizeof ("src/plugins/directoryvalue")) &&
+ strncmp (file, "src/plugins/yamlcpp/", sizeof ("src/plugins/yamlcpp")))
+ goto end;
+ #endif
+ ```
+
.
### Compilation
