Metadata-Version: 1.1
Name: strip-hints
Version: 0.1.5
Summary: Function and command-line program to strip Python type hints.
Home-page: https://github.com/abarker/strip-hints
Author: Allen Barker
Author-email: Allen.L.Barker@gmail.com
License: MIT
Description: 
        strip-hints
        ===========
        
        This package provides a command-line command and a corresponding importable
        function that strips type hints from Python code files.  The stripping process
        leaves runnable code, assuming the rest of the code is runnable in the
        interpreter version.  The program tries to make as few changes as possible to
        the processed code so that line and column numbers in error messages for the
        processed code file also correspond to those for the original code file.  In
        most cases, with the default options, both the line and column numbers are
        preserved.
        
        The stripping operation can be used as a preprocessor to allow the new type
        hint syntax to be used in Python 2.  The main intended application is for code
        which is being developed in Python 3 but which needs backward compatibility to
        Python 2.
        
        This project also contains a general-purpose class named ``TokenList`` which
        allows lists of Python tokens to be operated on using an interface similar to
        that of Python strings.  In particular, a ``split`` method is used for much of
        the processing in stripping hints.  This module could be useful for people
        doing other things with Python at the token level.
        
        Installing the code
        -------------------
        
        To install from PyPI using pip use::
        
           pip install strip-hints
        
        To install the most-recent development version first clone or download the
        project from `this GitHub repository
        <https://github.com/abarker/strip-hints>`_.
        
        Running the code
        ----------------
        
        After installing with pip you can run the console script ``strip-hints``::
        
           strip-hints your_file_with_hints.py
        
        The code runs with Python 2 and Python 3.  The processed code is written to
        stdout.  The AST checker that is run on the processed code checks the code
        against whatever version of Python the script is run with.
        
        The command-line options are as follows:
        
        ``--to-empty``
           Map removed code to empty strings rather than spaces.  This is easier to read,
           but does not preserve columns.  Default is false.
        
        ``--no-ast``
           Do not parse the resulting code with the Python ``ast`` module to check it.
           Default is false.
        
        ``--no-colon-move``
           Do not move colons to fix line breaks that occur in the hints for the
           function return type.  Default is false.
        
        ``--only-assigns-and-defs``
           Only strip annotated assignments and standalone type definitions, keeping
           function signature annotations.  Python 3.5 and earlier do not implement
           these; they first appeared in Python 3.6.  The default is false.
        
        ``--only-test-for-changes``
           Only test if any changes would be made.  If any stripping would be done then
           it prints ``True`` and exits with code 0.  Otherwise it prints ``False`` and
           exits with code 1.
        
        If you are using the development repo you can just run the file
        ``strip_hints.py`` in the ``bin`` directory of the repo::
        
           python strip_hints.py your_file_with_hints.py
        
        Alternately, you can install the development repo with pip::
        
           cd <pathToMainProjectDirectory> 
           pip install .  # use -e for development mode
        
        Automatically running on import
        -------------------------------
        
        A function can be called to automatically strip the type hints from all future
        imports that are in the same directory as the calling module.  For a package
        the function call can be placed in ``__init__.py``, for example.
        
        The function can be called as follows, with options set as desired (these
        are the default settings)::
        
           from strip_hints import strip_on_import
           strip_on_import(__file__, to_empty=False, no_ast=False, no_colon_move=False,
                           only_assigns_and_defs=False, py3_also=False)
        
        By default Python 3 code is ignored unless ``py3_also`` is set.  The first
        argument is the file path of the calling module.
        
        Calling from a Python program
        -----------------------------
        
        To strip the comments from a source file from within a Python program,
        returning a string containing the code, the functional interface is as follows.
        The option settings here are the default values::
        
           from strip_hints import strip_file_to_string
           code_string = strip_file_to_string(filename, to_empty=False, no_ast=False,
                                              no_colon_move=False, only_assigns_and_defs=False,
                                              only_test_for_changes=False)
        
        If ``only_test_for_changes`` is true then a boolean is returned which is true iff
        some changes would be made.
        
        Limitations
        -----------
        
        The program currently does not handle line breaks in annotated assignments when
        the code that is removed (the type specification) contains a line break that
        was formerly nested inside parens, brackets, or braces.  The program detects
        the situation and raises an exception.  As a workaround if necessary, using an
        explicit backslash line continuation seems to work.
        
        The same situation in the return type specification is handled by moving the
        colon token up to the line with the closing paren.  The situation does not
        occur inside parameter lists because they are always nested inside parentheses.
        
        The program currently only handles simple annotated expressions (e.g.,
        it handles ``my_class.x: int`` and ``my_list[2]: int`` but not ``(x): int``).
        
        How it works
        ------------
        
        Rather than doing a full, roundtrip parse, this module works on the tokens
        produced by the Python tokenizer.  Locating the relevant parts to remove is a
        much simpler task than parsing a program in full generality.  This allows an ad
        hoc approach based on splitting groups of tokens, taking into account the
        nesting level of the tokens to potentially split on.  Nesting level is based on
        the level count inside parentheses, brackets, and curly braces.
        
        * The tokenizer for Python 2 also works on code with type hints, as introduced in
          Python 3.
        
        * Type hints can be removed, in most cases, simply by turning some tokens into
          whitespace.  This preserves line and column numbers in the files.  Whiting-out a
          section of code with a non-nested line break either raises an exception or
          performs a slightly more-complicated transformation.
        
        In the most basic usage the sequence of tokens originally read from the file is
        never changed; some tokens just have their string values set to whitespace or
        to a pound sign before the untokenize operation.
        
        The gory details of the algorithm are discussed in the docstring for
        ``strip_hints_main.py``.  The method should be fairly robust.
        
        Bugs
        ----
        
        The code has been run on the Mypy source code and on some other examples, with
        the results parsed into ASTs and also visually inspected via diff.  Some edge
        cases may well remain to cause problems.  There is a Bash script in the ``test``
        directory which runs the program on files and shows the diffs.
        
        Possible enhancements
        ---------------------
        
        * Formal tests.
          
        * Better argument-handling, help, etc. with argparse.
        
        * Generate stubs for Python 2. (Unless the annotated files themselves will work as
          stubs; I haven't checked.)
        
        * Better error warnings (raising exceptions with messages rather than just failing
          assertions in some places).
        
        * More command options.
        
        
Keywords: type,hints,strip,annotations,typing
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: Unix
Classifier: Operating System :: POSIX
Classifier: Operating System :: Microsoft :: Windows
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Topic :: Utilities
