move @run_once from ipython_extension to misc.misc

It made the sympy interface depend on IPython...

Author: mezzarobba

src/sage/interfaces/sympy.py

@@ -1016,7 +1016,7 @@ def _sympysage_true(self):
 
 
 #------------------------------------------------------------------
-from sage.repl.ipython_extension import run_once
+from sage.misc.misc import run_once
 
 @run_once
 def sympy_init():

src/sage/misc/misc.py

@@ -38,6 +38,7 @@
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
+import functools
 import os
 import pdb
 import warnings
@@ -1132,3 +1133,37 @@ def inject_variable_test(name, value, depth):
         inject_variable(name, value)
     else:
         inject_variable_test(name, value, depth - 1)
+
+
+# from https://stackoverflow.com/questions/4103773/efficient-way-of-having-a-function-only-execute-once-in-a-loop
+def run_once(func):
+    """
+    Runs a function (successfully) only once.
+
+    The running can be reset by setting the ``has_run`` attribute to False
+
+    TESTS::
+
+        sage: from sage.repl.ipython_extension import run_once
+        sage: @run_once
+        ....: def foo(work):
+        ....:     if work:
+        ....:         return 'foo worked'
+        ....:     raise RuntimeError("foo didn't work")
+        sage: foo(False)
+        Traceback (most recent call last):
+        ...
+        RuntimeError: foo didn't work
+        sage: foo(True)
+        'foo worked'
+        sage: foo(False)
+        sage: foo(True)
+    """
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        if not wrapper.has_run:
+            result = func(*args, **kwargs)
+            wrapper.has_run = True
+            return result
+    wrapper.has_run = False
+    return wrapper

src/sage/repl/ipython_extension.py

@@ -68,6 +68,7 @@
 from sage.repl.load import load_wrap
 from sage.env import SAGE_IMPORTALL, SAGE_STARTUP_FILE
 from sage.misc.lazy_import import LazyImport
+from sage.misc.misc import run_once
 
 @magics_class
 class SageMagics(Magics):
@@ -583,41 +584,6 @@ def all_globals():
         return all_jupyter
 
 
-# from https://stackoverflow.com/questions/4103773/efficient-way-of-having-a-function-only-execute-once-in-a-loop
-from functools import wraps
-def run_once(func):
-    """
-    Runs a function (successfully) only once.
-
-    The running can be reset by setting the ``has_run`` attribute to False
-
-    TESTS::
-
-        sage: from sage.repl.ipython_extension import run_once
-        sage: @run_once
-        ....: def foo(work):
-        ....:     if work:
-        ....:         return 'foo worked'
-        ....:     raise RuntimeError("foo didn't work")
-        sage: foo(False)
-        Traceback (most recent call last):
-        ...
-        RuntimeError: foo didn't work
-        sage: foo(True)
-        'foo worked'
-        sage: foo(False)
-        sage: foo(True)
-    """
-    @wraps(func)
-    def wrapper(*args, **kwargs):
-        if not wrapper.has_run:
-            result = func(*args, **kwargs)
-            wrapper.has_run = True
-            return result
-    wrapper.has_run = False
-    return wrapper
-
-
 @run_once
 def load_ipython_extension(ip):
     """