Merge branch 'master' into stubgen-patch

.travis.yml

@@ -1,5 +1,7 @@
 sudo: false
 language: python
+# cache package wheels (1 cache per python version)
+cache: pip
 python:
   - "3.3"
   - "3.4"

appveyor.yml

@@ -1,34 +1,28 @@
 environment:
   matrix:
 
-    - PYTHON: "C:\\Python35"
-      PYTHON_VERSION: "3.5.1"
-      PYTHON_ARCH: "32"
-
-    - PYTHON: "C:\\Python35-x64"
-      PYTHON_VERSION: "3.5.1"
-      PYTHON_ARCH: "64"
-
     - PYTHON: "C:\\Python36"
       PYTHON_VERSION: "3.6.x"
       PYTHON_ARCH: "32"
-      
+
     - PYTHON: "C:\\Python36-x64"
       PYTHON_VERSION: "3.6.x"
       PYTHON_ARCH: "64"
-     
-     
+
+
 install:
+    - "git config core.symlinks true"
+    - "git reset --hard"
     - "%PYTHON%\\python.exe -m pip install -r test-requirements.txt"
     - "git submodule update --init typeshed"
+    - "cd typeshed && git config core.symlinks true && git reset --hard && cd .."
     - "%PYTHON%\\python.exe setup.py -q install"
-   
+
 build: off
 
 test_script:
-    # Ignore lint (it's run separately below)
+    # Ignore lint (it's run in Travis)
     - "%PYTHON%\\python.exe runtests.py -x lint"
-    - ps: if ($env:PYTHON_VERSION -Match "3.6.x" -And $env:PYTHON_ARCH -Match "64") { iex "$env:PYTHON\\python.exe -m flake8" }
 
 after_test:
   - "%PYTHON%\\python.exe -m pip install wheel"
@@ -37,3 +31,14 @@ after_test:
 
 artifacts:
   - path: dist\*
+
+skip_commits:
+  files:
+    - docs/**/*
+    - '**/*.rst'
+    - '**/*.md'
+    - .gitignore
+    - .runtest_log.json
+    - .travis.yml
+    - CREDITS
+    - LICENSE

docs/source/cheat_sheet.rst

@@ -134,7 +134,6 @@ When you're puzzled or when things are complicated
             # type: (*str, **str) -> str
             request = make_request(*args, **kwargs)
             return self.do_api_query(request)
-
    
    # Use `ignore` to suppress type-checking on a given line, when your
    # code confuses mypy or runs into an outright bug in mypy.

docs/source/cheat_sheet_py3.rst

@@ -122,6 +122,12 @@ When you're puzzled or when things are complicated
    # dynamic to write a type for.
    x = mystery_function()  # type: Any
 
+   # This is how to deal with varargs.
+   # This makes each positional arg and each keyword arg a 'str'.
+   def call(self, *args: str, **kwargs: str) -> str:
+            request = make_request(*args, **kwargs)
+            return self.do_api_query(request)
+
    # Use `ignore` to suppress type-checking on a given line, when your
    # code confuses mypy or runs into an outright bug in mypy.
    # Good practice is to comment every `ignore` with a bug link

docs/source/command_line.rst

@@ -21,7 +21,7 @@ flag (or its long form ``--help``)::
               [--inferstats] [--custom-typing MODULE]
               [--custom-typeshed-dir DIR] [--scripts-are-modules]
               [--config-file CONFIG_FILE] [--show-column-numbers]
-              [--find-occurrences CLASS.MEMBER] [--strict-boolean]
+              [--find-occurrences CLASS.MEMBER]
               [--cobertura-xml-report DIR] [--html-report DIR]
               [--linecount-report DIR] [--linecoverage-report DIR]
               [--memory-xml-report DIR] [--old-html-report DIR]
@@ -366,11 +366,6 @@ Here are some more useful flags:
 - ``--warn-return-any`` causes mypy to generate a warning when returning a value
   with type ``Any`` from a function declared with a non- ``Any`` return type.
 
-- ``--strict-boolean`` will make using non-boolean expressions in conditions
-  an error. This means ``if x`` and ``while x`` are disallowed when ``x`` has any
-  type other than ``bool``. Instead use explicit checks like ``if x > 0`` or
-  ``while x is not None``.
-
 - ``--strict`` mode enables all optional error checking flags.  You can see the
   list of flags enabled by strict mode in the full ``mypy -h`` output.
 

docs/source/function_overloading.rst

@@ -1,60 +1,90 @@
-Function overloading in stubs
-=============================
+Function Overloading
+====================
 
-Sometimes you have a library function that seems to call for two or
-more signatures.  That's okay -- you can define multiple *overloaded*
-instances of a function with the same name but different signatures in
-a stub file (this feature is not supported for user code, at least not
-yet) using the ``@overload`` decorator. For example, we can define an
-``abs`` function that works for both ``int`` and ``float`` arguments:
+Sometimes the types in a function depend on each other in ways that
+can't be captured with a ``Union``.  For example, the ``__getitem__``
+(``[]`` bracket indexing) method can take an integer and return a
+single item, or take a ``slice`` and return a ``Sequence`` of items.
+You might be tempted to annotate it like so:
 
 .. code-block:: python
 
-   # This is a stub file!
-
-   from typing import overload
-
-   @overload
-   def abs(n: int) -> int: pass
-
-   @overload
-   def abs(n: float) -> float: pass
-
-Note that we can't use ``Union[int, float]`` as the argument type,
-since this wouldn't allow us to express that the return
-type depends on the argument type.
-
-Now if we import ``abs`` as defined in the above library stub, we can
-write code like this, and the types are inferred correctly:
+    from typing import Sequence, TypeVar, Union
+    T = TypeVar('T')
+
+    class MyList(Sequence[T]):
+        def __getitem__(self, index: Union[int, slice]) -> Union[T, Sequence[T]]:
+            if isinstance(index, int):
+                ...  # Return a T here
+            elif isinstance(index, slice):
+                ...  # Return a sequence of Ts here
+            else:
+                raise TypeError(...)
+    
+But this is too loose, as it implies that when you pass in an ``int``
+you might sometimes get out a single item and sometimes a sequence.
+The return type depends on the parameter type in a way that can't be
+expressed using a type variable.  Instead, we can use `overloading
+<https://www.python.org/dev/peps/pep-0484/#function-method-overloading>`_
+to give the same function multiple type annotations (signatures) and
+accurately describe the function's behavior.
 
 .. code-block:: python
 
-   n = abs(-2)     # 2 (int)
-   f = abs(-1.5)   # 1.5 (float)
+    from typing import overload, Sequence, TypeVar, Union
+    T = TypeVar('T')
+
+    class MyList(Sequence[T]):
+
+        # The @overload definitions are just for the type checker,
+        # and overwritten by the real implementation below.
+        @overload
+        def __getitem__(self, index: int) -> T:
+            pass  # Don't put code here
+
+        # All overloads and the implementation must be adjacent
+        # in the source file, and overload order may matter:
+        # when two overloads may overlap, the more specific one
+        # should come first.
+        @overload
+        def __getitem__(self, index: slice) -> Sequence[T]:
+            pass  # Don't put code here
+
+        # The implementation goes last, without @overload.
+        # It may or may not have type hints; if it does,
+        # these are checked against the overload definitions
+        # as well as against the implementation body.
+        def __getitem__(self, index):
+            # This is exactly the same as before.
+            if isinstance(index, int):
+                ...  # Return a T here
+            elif isinstance(index, slice):
+                ...  # Return a sequence of Ts here
+            else:
+                raise TypeError(...)
 
 Overloaded function variants are still ordinary Python functions and
-they still define a single runtime object. The following code is
-thus valid:
-
-.. code-block:: python
-
-   my_abs = abs
-   my_abs(-2)      # 2 (int)
-   my_abs(-1.5)    # 1.5 (float)
+they still define a single runtime object. There is no automatic
+dispatch happening, and you must manually handle the different types
+in the implementation (usually with :func:`isinstance` checks, as
+shown in the example).
 
 The overload variants must be adjacent in the code. This makes code
 clearer, as you don't have to hunt for overload variants across the
 file.
 
+Overloads in stub files are exactly the same, except there is no
+implementation.
+
 .. note::
 
    As generic type variables are erased at runtime when constructing
    instances of generic types, an overloaded function cannot have
    variants that only differ in a generic type argument,
-   e.g. ``List[int]`` versus ``List[str]``.
+   e.g. ``List[int]`` and ``List[str]``.
 
 .. note::
 
-   If you are writing a regular module rather than a stub, you can
-   often use a type variable with a value restriction to represent
-   functions as ``abs`` above (see :ref:`type-variable-value-restriction`).
+   If you just need to constrain a type variable to certain types or
+   subtypes, you can use a :ref:`value restriction
+   <type-variable-value-restriction>`.

docs/source/revision_history.rst

@@ -3,6 +3,9 @@ Revision history
 
 List of major changes to this document:
 
+- April 2017
+    * Remove option ``strict_boolean``.
+
 - March 2017
     * Publish ``mypy`` version 0.500 on PyPI.
 

mypy/build.py

@@ -860,8 +860,7 @@ def write_cache(id: str, path: str, tree: MypyFile,
 
     # Make sure directory for cache files exists
     parent = os.path.dirname(data_json)
-    if not os.path.isdir(parent):
-        os.makedirs(parent)
+    os.makedirs(parent, exist_ok=True)
     assert os.path.dirname(meta_json) == parent
 
     # Construct temp file names
@@ -877,6 +876,20 @@ def write_cache(id: str, path: str, tree: MypyFile,
         data_str = json.dumps(data, sort_keys=True)
     interface_hash = compute_hash(data_str)
 
+    # Obtain and set up metadata
+    try:
+        st = manager.get_stat(path)
+    except OSError as err:
+        manager.log("Cannot get stat for {}: {}".format(path, err))
+        # Remove apparently-invalid cache files.
+        for filename in [data_json, meta_json]:
+            try:
+                os.remove(filename)
+            except OSError:
+                pass
+        # Still return the interface hash we computed.
+        return interface_hash
+
     # Write data cache file, if applicable
     if old_interface_hash == interface_hash:
         # If the interface is unchanged, the cached data is guaranteed
@@ -891,8 +904,6 @@ def write_cache(id: str, path: str, tree: MypyFile,
         os.replace(data_json_tmp, data_json)
         manager.trace("Interface for {} has changed".format(id))
 
-    # Obtain and set up metadata
-    st = manager.get_stat(path)  # TODO: Handle errors
     mtime = st.st_mtime
     size = st.st_size
     options = manager.options.clone_for_module(id)
@@ -1524,26 +1535,26 @@ def valid_references(self) -> Set[str]:
         return valid_refs
 
     def write_cache(self) -> None:
-        ok = self.path and self.options.incremental
-        if ok:
-            if self.manager.options.quick_and_dirty:
-                is_errors = self.manager.errors.is_errors_for_file(self.path)
-            else:
-                is_errors = self.manager.errors.is_errors()
-            ok = not is_errors
-        if ok:
-            dep_prios = [self.priorities.get(dep, PRI_HIGH) for dep in self.dependencies]
-            new_interface_hash = write_cache(
-                self.id, self.path, self.tree,
-                list(self.dependencies), list(self.suppressed), list(self.child_modules),
-                dep_prios, self.interface_hash,
-                self.manager)
-            if new_interface_hash == self.interface_hash:
-                self.manager.log("Cached module {} has same interface".format(self.id))
-            else:
-                self.manager.log("Cached module {} has changed interface".format(self.id))
-                self.mark_interface_stale()
-                self.interface_hash = new_interface_hash
+        if not self.path or self.options.cache_dir == os.devnull:
+            return
+        if self.manager.options.quick_and_dirty:
+            is_errors = self.manager.errors.is_errors_for_file(self.path)
+        else:
+            is_errors = self.manager.errors.is_errors()
+        if is_errors:
+            return
+        dep_prios = [self.priorities.get(dep, PRI_HIGH) for dep in self.dependencies]
+        new_interface_hash = write_cache(
+            self.id, self.path, self.tree,
+            list(self.dependencies), list(self.suppressed), list(self.child_modules),
+            dep_prios, self.interface_hash,
+            self.manager)
+        if new_interface_hash == self.interface_hash:
+            self.manager.log("Cached module {} has same interface".format(self.id))
+        else:
+            self.manager.log("Cached module {} has changed interface".format(self.id))
+            self.mark_interface_stale()
+            self.interface_hash = new_interface_hash
 
 
 def dispatch(sources: List[BuildSource], manager: BuildManager) -> Graph: