suppress syntax warnings thrown by compile

tests/test_contexts.py

@@ -4,7 +4,7 @@ from nose.tools import assert_equal, assert_is, assert_is_not
 from tools import (mock_xonsh_env, execer_setup, check_exec, check_eval,
     check_parse, skip_if)
 
-from xonsh.contexts import Block
+from xonsh.contexts import Block, Functor
 
 #
 # helpers
@@ -61,7 +61,7 @@ def block_checks_func(name, glbs, body, obsg=None, obsl=None):
 
 
 #
-# tests
+# Block tests
 #
 
 def test_block_noexec():
@@ -231,3 +231,46 @@ def test_block_func_trailing_triple_string():
     glbs = {'Block': Block}
     check_exec(s, glbs=glbs, locs=None)
     yield from block_checks_func('rtn', glbs, body, FUNC_OBSG, FUNC_OBSL)
+
+
+#
+# Functor tests
+#
+
+X2_WITH = ('x = 1\n'
+           'with Functor() as f:\n'
+           '{body}'
+           'x += 1\n'
+           '{calls}\n'
+           )
+
+def test_functor_oneline_onecall_class():
+    body = ('    global x\n'
+            '    x += 42\n')
+    calls = 'f()'
+    s = X2_WITH.format(body=body, calls=calls)
+    glbs = {'Functor': Functor}
+    check_exec(s, glbs=glbs, locs=None)
+    yield from block_checks_glb('f', glbs, body, {'x': 44})
+
+
+def test_functor_oneline_onecall_func():
+    body = ('    global x\n'
+            '    x += 42\n')
+    calls = 'f.func()'
+    s = X2_WITH.format(body=body, calls=calls)
+    glbs = {'Functor': Functor}
+    check_exec(s, glbs=glbs, locs=None)
+    yield from block_checks_glb('f', glbs, body, {'x': 44})
+
+
+def test_functor_oneline_onecall_both():
+    body = ('    global x\n'
+            '    x += 42\n')
+    calls = 'f()\nf.func()'
+    s = X2_WITH.format(body=body, calls=calls)
+    glbs = {'Functor': Functor}
+    check_exec(s, glbs=glbs, locs=None)
+    yield from block_checks_glb('f', glbs, body, {'x': 86})
+
+

xonsh/contexts.py

@@ -1,4 +1,5 @@
 """Context management tools for xonsh."""
+import sys
 import builtins
 
 from xonsh.tools import XonshBlockError
@@ -9,7 +10,7 @@ class Block(object):
     """
     __xonsh_block__ = True
 
-    def __init__(self, lines=None):
+    def __init__(self):
         """
         Attributes
         ----------
@@ -35,3 +36,55 @@ class Block(object):
             # leave locals as None when it is the same as globals
             self.locs = exc_value.locs
         return True
+
+
+class Functor(Block):
+    """This is a context manager that turns the block into a callable
+    object, bound to the execution context it was created in.
+    """
+
+    def __init__(self):
+        """
+        Attributes
+        ----------
+        func : function
+            The underlying function object. This defaults to none and is set
+            after the the block is exited.
+        """
+        super().__init__()
+        self.func = None
+
+    def __enter__(self):
+        super().__enter__()
+        self.func = None
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        rtn = super().__exit__(exc_type, exc_value, traceback)
+        if not rtn:
+            return rtn
+        body = '\n'.join(self.lines)
+        uid = hash(body) + sys.maxsize  # should always be a positive int
+        name = '__xonsh_functor_{uid}__'.format(uid=uid)
+        fstr = 'def {name}():\n{body}\n'
+        fstr = fstr.format(name=name, body=body)
+        glbs = self.glbs
+        locs = self.locs
+        #locs = glbs if self.locs is None else self.locs
+        execer = builtins.__xonsh_execer__
+        execer.exec(fstr, glbs=glbs, locs=locs)
+        if locs is not None and name in locs:
+            func = locs[name]
+        elif name in glbs:
+            func = glbs[name]
+        else:
+            raise exc_value
+        self.func = func
+        return rtn
+
+    def __call__(self, *args, **kwargs):
+        """Dispatches to func."""
+        if self.func is None:
+            msg = "{} block with 'None' func not callable"
+            raise AttributeError(msg.formst(self.__class__.__name__))
+        return self.func(*args, **kwargs)

xonsh/execer.py

@@ -5,6 +5,7 @@ import sys
 import types
 import inspect
 import builtins
+import warnings
 from collections import Mapping
 
 from xonsh import ast
@@ -100,6 +101,12 @@ class Execer(object):
         tree = self.parse(input, ctx, mode=mode, transform=transform)
         if tree is None:
             return None  # handles comment only input
+        if transform:
+            with warnings.catch_warnings():
+                # we do some funky things with blocks that cause warnings
+                warnings.simplefilter('ignore', SyntaxWarning)
+                code = compile(tree, filename, mode)
+        else:
             code = compile(tree, filename, mode)
         return code