support signatures in method decorator

Author: Anders Hellerup Madsen

dbus_next/service.py

@@ -6,32 +6,47 @@
 
 from functools import wraps
 import inspect
-from typing import no_type_check_decorator, Dict, List, Any
+from typing import no_type_check_decorator, Dict, List, Any, Optional
 import copy
 import asyncio
 
 
 class _Method:
-    def __init__(self, fn, name, disabled=False):
-        in_signature = ''
-        out_signature = ''
+    def __init__(self,
+                 fn,
+                 name,
+                 disabled=False,
+                 in_signature: Optional[str] = None,
+                 out_signature: Optional[str] = None):
 
         inspection = inspect.signature(fn)
 
-        in_args = []
-        for i, param in enumerate(inspection.parameters.values()):
-            if i == 0:
-                # first is self
-                continue
-            annotation = parse_annotation(param.annotation)
-            if not annotation:
-                raise ValueError(
-                    'method parameters must specify the dbus type string as an annotation')
-            in_args.append(intr.Arg(annotation, intr.ArgDirection.IN, param.name))
-            in_signature += annotation
+        if in_signature is None:
+            in_signature = ''
+            in_args = []
+            for i, param in enumerate(inspection.parameters.values()):
+                if i == 0:
+                    # first is self
+                    continue
+                annotation = parse_annotation(param.annotation)
+                if not annotation:
+                    raise ValueError(
+                        'method parameters must specify the dbus type string as an annotation')
+                in_args.append(intr.Arg(annotation, intr.ArgDirection.IN, param.name))
+                in_signature += annotation
+        else:
+            name_iter = iter(inspection.parameters.keys())
+            next(name_iter)  # skip self parameter
+            in_args = [
+                intr.Arg(type_, intr.ArgDirection.IN, name)
+                for name, type_ in zip(name_iter,
+                                       SignatureTree._get(in_signature).types)
+            ]
+
+        if out_signature is None:
+            out_signature = parse_annotation(inspection.return_annotation)
 
         out_args = []
-        out_signature = parse_annotation(inspection.return_annotation)
         if out_signature:
             for type_ in SignatureTree._get(out_signature).types:
                 out_args.append(intr.Arg(type_, intr.ArgDirection.OUT))
@@ -41,12 +56,15 @@ def __init__(self, fn, name, disabled=False):
         self.disabled = disabled
         self.introspection = intr.Method(name, in_args, out_args)
         self.in_signature = in_signature
-        self.out_signature = out_signature
         self.in_signature_tree = SignatureTree._get(in_signature)
+        self.out_signature = out_signature
         self.out_signature_tree = SignatureTree._get(out_signature)
 
 
-def method(name: str = None, disabled: bool = False):
+def method(name: str = None,
+           disabled: bool = False,
+           in_signature: Optional[str] = None,
+           out_signature: Optional[str] = None):
     """A decorator to mark a class method of a :class:`ServiceInterface` to be a DBus service method.
 
     The parameters and return value must each be annotated with a signature
@@ -91,7 +109,12 @@ def wrapped(*args, **kwargs):
             fn(*args, **kwargs)
 
         fn_name = name if name else fn.__name__
-        wrapped.__dict__['__DBUS_METHOD'] = _Method(fn, fn_name, disabled=disabled)
+        _method = _Method(fn,
+                          fn_name,
+                          disabled=disabled,
+                          in_signature=in_signature,
+                          out_signature=out_signature)
+        wrapped.__dict__['__DBUS_METHOD'] = _method
 
         return wrapped
 

test/service/test_decorators.py

@@ -1,6 +1,8 @@
 from dbus_next import PropertyAccess, introspection as intr
 from dbus_next.service import method, signal, dbus_property, ServiceInterface
 
+from typing import List
+
 
 class ExampleInterface(ServiceInterface):
     def __init__(self):
@@ -17,6 +19,10 @@ def some_method(self, one: 's', two: 's') -> 's':
     def another_method(self, eight: 'o', six: 't'):
         pass
 
+    @method(in_signature="sasu", out_signature="i")
+    def a_third_method(self, one: str, two: List[str], three) -> int:
+        return 42
+
     @signal()
     def some_signal(self) -> 'as':
         return ['result']
@@ -56,16 +62,25 @@ def test_method_decorator():
     methods = ServiceInterface._get_methods(interface)
     signals = ServiceInterface._get_signals(interface)
 
-    assert len(methods) == 2
+    assert len(methods) == 3
 
     method = methods[0]
+    assert method.name == 'a_third_method'
+    assert method.in_signature == 'sasu'
+    assert method.out_signature == 'i'
+    assert not method.disabled
+    assert type(method.introspection) is intr.Method
+    assert len(method.introspection.in_args) == 3
+    assert len(method.introspection.out_args) == 1
+
+    method = methods[1]
     assert method.name == 'renamed_method'
     assert method.in_signature == 'ot'
     assert method.out_signature == ''
     assert method.disabled
     assert type(method.introspection) is intr.Method
 
-    method = methods[1]
+    method = methods[2]
     assert method.name == 'some_method'
     assert method.in_signature == 'ss'
     assert method.out_signature == 's'
@@ -142,7 +157,7 @@ def test_interface_introspection():
     signals = xml.findall('signal')
     properties = xml.findall('property')
 
-    assert len(xml) == 4
-    assert len(methods) == 1
+    assert len(xml) == 5
+    assert len(methods) == 2
     assert len(signals) == 1
     assert len(properties) == 2