0.15.1: .catch: add 'when' param

streamable/functions.py

@@ -36,11 +36,13 @@
 def catch(
     iterator: Iterator[T],
     kind: Type[Exception] = Exception,
+    when: Callable[[Exception], Any] = bool,
     finally_raise: bool = False,
 ) -> Iterator[T]:
     return CatchingIterator(
         iterator,
         kind,
+        when,
         finally_raise=finally_raise,
     )
 

streamable/iters.py

@@ -33,10 +33,12 @@ def __init__(
         self,
         iterator: Iterator[T],
         kind: Type[Exception],
+        when: Callable[[Exception], Any],
         finally_raise: bool,
     ) -> None:
         self.iterator = iterator
         self.kind = kind
+        self.when = when
         self.finally_raise = finally_raise
         self._to_be_finally_raised: Optional[Exception] = None
 
@@ -51,7 +53,7 @@ def __next__(self) -> T:
                     raise exception
                 raise
             except Exception as exception:
-                if isinstance(exception, self.kind):
+                if isinstance(exception, self.kind) and self.when(exception):
                     if self._to_be_finally_raised is None:
                         self._to_be_finally_raised = exception
                     continue

streamable/stream.py

@@ -105,19 +105,21 @@ def accept(self, visitor: "Visitor[V]") -> V:
     def catch(
         self,
         kind: Type[Exception] = Exception,
+        when: Callable[[Exception], Any] = bool,
         finally_raise: bool = False,
     ) -> "Stream[T]":
         """
-        Catches the upstream exceptions if they are instances of `kind`.
+        Catches the upstream exceptions if they are instances of `kind` and they satisfy the `when` predicate.
 
         Args:
-            kind (Type[Exception], optional): The type of exceptions to catch (default is all non-exit exceptions).
+            kind (Type[Exception], optional): The type of exceptions to catch (default is base Exception).
+            when (Callable[[Exception], Any], optional): An additional condition that must be satisfied (`when(exception)` must be Truthy) to catch the exception (Always satisfied by default).
             finally_raise (bool, optional): If True the first catched exception is raised when upstream's iteration ends (default is False).
 
         Returns:
             Stream[T]: A stream of upstream elements catching the eligible exceptions.
         """
-        return CatchStream(self, kind, finally_raise)
+        return CatchStream(self, kind, when, finally_raise)
 
     def filter(self, keep: Callable[[T], Any] = bool) -> "Stream[T]":
         """
@@ -369,19 +371,19 @@ def __init__(
         self,
         upstream: Stream[T],
         kind: Type[Exception],
+        when: Callable[[Exception], Any],
         finally_raise: bool,
     ) -> None:
         super().__init__(upstream)
         self.kind = kind
+        self.when = when
         self.finally_raise = finally_raise
 
     def accept(self, visitor: "Visitor[V]") -> V:
         return visitor.visit_catch_stream(self)
 
     def __repr__(self) -> str:
-        call = (
-            f"catch({friendly_string(self.kind)}, finally_raise={self.finally_raise})"
-        )
+        call = f"catch({friendly_string(self.kind)}, when={friendly_string(self.when)}, finally_raise={self.finally_raise})"
         return f"{repr(self.upstream)}\\\n.{call}"
 
 

streamable/visitors/iterator.py

@@ -26,6 +26,7 @@ def visit_catch_stream(self, stream: CatchStream[T]) -> Iterator[T]:
         return functions.catch(
             stream.upstream.accept(self),
             stream.kind,
+            stream.when,
             finally_raise=stream.finally_raise,
         )
 

tests/test_stream.py

@@ -972,6 +972,16 @@ def f(i):
         ):
             next(iterator)
 
+        with self.assertRaises(
+            TypeError,
+            msg="`catch` does not catch if `when` not satisfied",
+        ):
+            list(
+                Stream(map(throw, [ValueError, TypeError])).catch(
+                    Exception, when=lambda exception: "ValueError" in repr(exception)
+                )
+            )
+
     def test_observe(self) -> None:
         value_error_rainsing_stream: Stream[List[int]] = (
             Stream("123--567")

version.py

@@ -1 +1 @@
-__version__ = "0.15.0"
+__version__ = "0.15.1"