Add "default" arg to return value in "catch()" on error (#272)

CHANGELOG.rst

@@ -1,3 +1,9 @@
+`Unreleased`_
+=============
+
+- Add a new ``default`` optional argument to ``logger.catch()``, it should be the returned value by the decorated function in case an error occurred (`#272 <https://github.com/Delgan/loguru/issues/272>`_).
+
+
 `0.5.0`_ (2020-05-17)
 =====================
 

loguru/_logger.py

@@ -1078,6 +1078,7 @@ def catch(
         reraise=False,
         onerror=None,
         exclude=None,
+        default=None,
         message="An error has been caught in function '{record[function]}', "
         "process '{record[process].name}' ({record[process].id}), "
         "thread '{record[thread].name}' ({record[thread].id}):"
@@ -1108,6 +1109,9 @@ def catch(
         exclude : |Exception|, optional
             A type of exception (or a tuple of types) that will be purposely ignored and hence
             propagated to the caller without being logged.
+        default : optional
+            The value to be returned by the decorated function if an error occurred without being
+            re-raised.
         message : |str|, optional
             The message that will be automatically logged if an exception occurs. Note that it will
             be formatted with the ``record`` attribute.
@@ -1196,18 +1200,21 @@ def __call__(_, function):
                     async def catch_wrapper(*args, **kwargs):
                         with catcher:
                             return await function(*args, **kwargs)
+                        return default
 
                 elif inspect.isgeneratorfunction(function):
 
                     def catch_wrapper(*args, **kwargs):
                         with catcher:
                             return (yield from function(*args, **kwargs))
+                        return default
 
                 else:
 
                     def catch_wrapper(*args, **kwargs):
                         with catcher:
                             return function(*args, **kwargs)
+                        return default
 
                 functools.update_wrapper(catch_wrapper, function)
                 return catch_wrapper

tests/test_catch_exceptions.py

@@ -623,3 +623,38 @@ def foo(x, y, z):
 
     with pytest.raises(StopIteration, match=r"3"):
         next(f)
+
+
+def test_decorate_generator_with_error():
+    @logger.catch
+    def foo():
+        for i in range(3):
+            1 / (2 - i)
+            yield i
+
+    assert list(foo()) == [0, 1]
+
+
+def test_default_with_function():
+    @logger.catch(default=42)
+    def foo():
+        1 / 0
+
+    assert foo() == 42
+
+
+def test_default_with_generator():
+    @logger.catch(default=42)
+    def foo():
+        yield 1 / 0
+
+    with pytest.raises(StopIteration, match=r"42"):
+        next(foo())
+
+
+def test_default_with_coroutine():
+    @logger.catch(default=42)
+    async def foo():
+        return 1 / 0
+
+    assert asyncio.run(foo()) == 42