plugins: added `warningf` explanation
@@ -360,7 +360,8 @@ be called and the mounted file will be updated.
We haven't discussed `ELEKTRA_SET_<CONCRETE>_ERROR` yet. Because Elektra is a library, printing errors to stderr wouldn't be a good idea. Instead, errors
and warnings can be appended to a key in the form of metadata. This is what `ELEKTRA_SET_<CONCRETE>_ERROR` does. The `<CONCRETE>` in the
-text means the concrete error type such as `RESOURCE`, `INSTALLATION`, etc.
+text means the concrete error type such as `RESOURCE`, `INSTALLATION`, etc. Note that you also have a varargs macro with `...ERRORF`
+that allows you to insert a string and substitute parts with variables.
You can see all available error types as well as their categorization guidelines [here](/doc/dev/error-categorization.md).
Because the parentKey always exists
even if a critical error occurs, we write the error to the parentKey. The error does not necessarily have to be in a configuration.
@@ -423,7 +424,8 @@ keyNew ("system/elektra/modules/" ELEKTRA_PLUGIN_NAME "/exports/checkconf", KEY_
Within the `checkconf` function all of the plugin configuration values should be validated.
Errors should be reported via Elektra's error handling mechanism (see section [ELEKTRA*SET*<CONCRETE>\_ERROR](#elektra_set_concrete_error) for further details).
If `checkconf` encounters a configuration value, that is not strictly invalid but can not be parsed by the plugin (e.g. a parameter which is not part of the plugin configuration),
-then a warning should be appended to `errorKey`, using `ELEKTRA_ADD_<CONCRETE>_WARNING`.
+then a warning should be appended to `errorKey`, using `ELEKTRA_ADD_<CONCRETE>_WARNING`. You also have a `...WARNINGF` vararg macro that
+allows you to substitute parts of the message with variables.
### `ELEKTRA_PLUGIN_EXPORT`
