Implementing decorator

IPython/core/displayhook.py

@@ -91,7 +91,13 b' class DisplayHook(Configurable):'
             # some uses of ipshellembed may fail here
             return False
         
-        sio = _io.StringIO(cell)
+        return self.semicolon_at_end_of_expression(cell)
+        
+    @staticmethod
+    def semicolon_at_end_of_expression(expression):
+        """Parse Python expression and detects whether last token is ';'"""
+
+        sio = _io.StringIO(expression)
         tokens = list(tokenize.generate_tokens(sio.readline))
 
         for token in reversed(tokens):

IPython/core/interactiveshell.py

@@ -2363,11 +2363,11 b' class InteractiveShell(SingletonConfigurable):'
             with self.builtin_trap:
                 result = fn(*args, **kwargs)
 
-            # The code below prevents output from being displayed
-            # when using magic %time.
-            # Output from '%time foo();', for instance, would never
-            # be displayed.
-            if magic_name == "time" and len(magic_arg_s) > 0 and magic_arg_s[-1] == ";":
+            # The code below prevents the output from being displayed
+            # when using magics with decodator @output_can_be_disabled
+            # when the last Python token in the expression is a ';'.
+            if getattr(fn, magic.MAGIC_OUTPUT_CAN_BE_DISABLED, False):
+                if DisplayHook.semicolon_at_end_of_expression(magic_arg_s):
                 return None
 
             return result

IPython/core/magic.py

@@ -258,7 +258,7 b' def _function_magic_marker(magic_kind):'
 
 
 MAGIC_NO_VAR_EXPAND_ATTR = '_ipython_magic_no_var_expand'
-
+MAGIC_OUTPUT_CAN_BE_DISABLED = '_ipython_magic_output_can_be_disabled'
 
 def no_var_expand(magic_func):
     """Mark a magic function as not needing variable expansion
@@ -275,6 +275,15 b' def no_var_expand(magic_func):'
     setattr(magic_func, MAGIC_NO_VAR_EXPAND_ATTR, True)
     return magic_func
 
+def output_can_be_disabled(magic_func):
+    """Mark a magic function so its output may be disabled.
+
+    The output is disabled if the Python expression used as a parameter of
+    the magic ends in a semicolon, not counting a Python comment that can
+    follows it.
+    """
+    setattr(magic_func, MAGIC_OUTPUT_CAN_BE_DISABLED, True)
+    return magic_func
 
 # Create the actual decorators for public use
 

IPython/core/magics/execution.py

@@ -37,6 +37,7 b' from IPython.core.magic import ('
     magics_class,
     needs_local_scope,
     no_var_expand,
+    output_can_be_disabled,
     on_off,
 )
 from IPython.testing.skipdoctest import skip_doctest
@@ -1194,6 +1195,7 b' class ExecutionMagics(Magics):'
     @no_var_expand
     @needs_local_scope
     @line_cell_magic
+    @output_can_be_disabled
     def time(self,line='', cell=None, local_ns=None):
         """Time execution of a Python statement or expression.
 

IPython/core/tests/test_magic.py

@@ -419,7 +419,7 b' def test_time():'
 
 # ';' at the end of %time prevents instruction value to be printed.
 # This tests fix for #13837.
-def test_time_no_outputwith_semicolon():
+def test_time_no_output_with_semicolon():
     ip = get_ipython()
 
     with tt.AssertPrints(" 123456"):
@@ -432,6 +432,21 b' def test_time_no_outputwith_semicolon():'
             with tt.AssertPrints("CPU times: ", suppress=False):
                 ip.run_cell("%time 123000+456;")
 
+    with tt.AssertPrints(" 123456"):
+        with tt.AssertPrints("Wall time: ", suppress=False):
+            with tt.AssertPrints("CPU times: ", suppress=False):
+                ip.run_cell("%time 123000+456 # Comment")
+
+    with tt.AssertNotPrints(" 123456"):
+        with tt.AssertPrints("Wall time: ", suppress=False):
+            with tt.AssertPrints("CPU times: ", suppress=False):
+                ip.run_cell("%time 123000+456; # Comment")
+
+    with tt.AssertPrints(" 123456"):
+        with tt.AssertPrints("Wall time: ", suppress=False):
+            with tt.AssertPrints("CPU times: ", suppress=False):
+                ip.run_cell("%time 123000+456 # ;Comment")
+
 
 def test_time_last_not_expression():
     ip.run_cell("%%time\n"