Explicit notion of abstract classes

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/checks/base.py

@@ -65,13 +65,13 @@ class Check(object):
         '''
         Check for single phrase, not dealing with plurals.
         '''
-        return False
+        raise NotImplementedError()
 
     def check_source(self, source, unit):
         '''
         Checks source string
         '''
-        return False
+        raise NotImplementedError()
 
     def check_chars(self, source, target, pos, chars):
         '''
@@ -130,6 +130,18 @@ class TargetCheck(Check):
     '''
     target = True
 
+    def check_source(self, source, unit):
+        '''
+        We don't check source strings here.
+        '''
+        return False
+
+    def check_single(self, source, target, unit, cache_slot):
+        '''
+        Check for single phrase, not dealing with plurals.
+        '''
+        raise NotImplementedError()
+
 
 class SourceCheck(Check):
     '''
@@ -137,6 +149,18 @@ class SourceCheck(Check):
     '''
     source = True
 
+    def check_single(self, source, target, unit, cache_slot):
+        '''
+        We don't check target strings here.
+        '''
+        return False
+
+    def check_source(self, source, unit):
+        '''
+        Checks source string
+        '''
+        raise NotImplementedError()
+
 
 class CountingCheck(TargetCheck):
     '''

weblate/trans/checks/consistency.py

@@ -40,6 +40,12 @@ class PluralsCheck(TargetCheck):
         # Check for empty translation
         return '' in targets
 
+    def check_single(self, source, target, unit, cache_slot):
+        '''
+        We don't check target strings here.
+        '''
+        return False
+
 
 class ConsistencyCheck(TargetCheck):
     '''
@@ -72,3 +78,9 @@ class ConsistencyCheck(TargetCheck):
                     return True
 
         return False
+
+    def check_single(self, source, target, unit, cache_slot):
+        '''
+        We don't check target strings here.
+        '''
+        return False

weblate/trans/checks/format.py

@@ -206,6 +206,12 @@ class BaseFormatCheck(TargetCheck):
     def is_position_based(self, string):
         return True
 
+    def check_single(self, source, target, unit, cache_slot):
+        '''
+        We don't check target strings here.
+        '''
+        return False
+
 
 class PythonFormatCheck(BaseFormatCheck):
     '''