refactor: change meta class structure to include types.

Introduce requiredness of translations via implemented interface.

src/core/things/Semester.ts

@@ -12,8 +12,9 @@
  * You should have received a copy of the GNU General Public License along with
  * this program. If not, see <https://www.gnu.org/licenses/>.
  */
-import {SCAcademicTermWithoutReferences} from '../base/AcademicTerm';
+import {SCAcademicTermWithoutReferences, SCAcademicTermWithoutReferencesMeta} from '../base/AcademicTerm';
 import {SCThingMeta, SCThingType} from '../Thing';
+import {SCMetaTranslations} from '../types/i18n';
 
 /**
  * A semester without references
@@ -45,17 +46,37 @@ export interface SCSemester extends SCSemesterWithoutReferences {
 }
 
 /**
- * Semester meta data
+ * Meta information about a semester
  */
-export class SCSemesterMeta extends SCThingMeta {
-  static fieldTranslations = {
-    ...SCThingMeta.fieldTranslations,
+export class SCSemesterMeta extends SCThingMeta implements SCMetaTranslations<SCSemester> {
+  /**
+   * Translations of fields
+   */
+  fieldTranslations = {
     de: {
+      ... SCAcademicTermWithoutReferencesMeta.getInstance().fieldTranslations.de,
       acronym: 'Abkürzung',
       endDate: 'Ende',
       eventsEndDate: 'Vorlesungsschluss',
       eventsStartDate: 'Vorlesungsbeginn',
       startDate: 'Beginn',
     },
+    en: {
+      ... SCAcademicTermWithoutReferencesMeta.getInstance().fieldTranslations.en,
+    },
+  };
+
+  /**
+   * Translations of values of fields
+   */
+  fieldValueTranslations  = {
+    de: {
+      ... SCAcademicTermWithoutReferencesMeta.getInstance().fieldValueTranslations.de,
+      type: 'Semester',
+    },
+    en: {
+      ... SCAcademicTermWithoutReferencesMeta.getInstance().fieldValueTranslations.en,
+      type: SCThingType.Semester,
+    },
   };
 }