add ydb deps

1 files changed, 757 insertions, 0 deletions

diff --git a/contrib/python/ipython/py3/IPython/core/magic.py b/contrib/python/ipython/py3/IPython/core/magic.py
new file mode 100644
index 0000000000..4f9e4e548f
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/core/magic.py
@@ -0,0 +1,757 @@
+# encoding: utf-8
+"""Magic functions for InteractiveShell.
+"""
+
+#-----------------------------------------------------------------------------
+#  Copyright (C) 2001 Janko Hauser <jhauser@zscout.de> and
+#  Copyright (C) 2001 Fernando Perez <fperez@colorado.edu>
+#  Copyright (C) 2008 The IPython Development Team
+
+#  Distributed under the terms of the BSD License.  The full license is in
+#  the file COPYING, distributed as part of this software.
+#-----------------------------------------------------------------------------
+
+import os
+import re
+import sys
+from getopt import getopt, GetoptError
+
+from traitlets.config.configurable import Configurable
+from . import oinspect
+from .error import UsageError
+from .inputtransformer2 import ESC_MAGIC, ESC_MAGIC2
+from ..utils.ipstruct import Struct
+from ..utils.process import arg_split
+from ..utils.text import dedent
+from traitlets import Bool, Dict, Instance, observe
+from logging import error
+
+#-----------------------------------------------------------------------------
+# Globals
+#-----------------------------------------------------------------------------
+
+# A dict we'll use for each class that has magics, used as temporary storage to
+# pass information between the @line/cell_magic method decorators and the
+# @magics_class class decorator, because the method decorators have no
+# access to the class when they run.  See for more details:
+# http://stackoverflow.com/questions/2366713/can-a-python-decorator-of-an-instance-method-access-the-class
+
+magics = dict(line={}, cell={})
+
+magic_kinds = ('line', 'cell')
+magic_spec = ('line', 'cell', 'line_cell')
+magic_escapes = dict(line=ESC_MAGIC, cell=ESC_MAGIC2)
+
+#-----------------------------------------------------------------------------
+# Utility classes and functions
+#-----------------------------------------------------------------------------
+
+class Bunch: pass
+
+
+def on_off(tag):
+    """Return an ON/OFF string for a 1/0 input. Simple utility function."""
+    return ['OFF','ON'][tag]
+
+
+def compress_dhist(dh):
+    """Compress a directory history into a new one with at most 20 entries.
+
+    Return a new list made from the first and last 10 elements of dhist after
+    removal of duplicates.
+    """
+    head, tail = dh[:-10], dh[-10:]
+
+    newhead = []
+    done = set()
+    for h in head:
+        if h in done:
+            continue
+        newhead.append(h)
+        done.add(h)
+
+    return newhead + tail
+
+
+def needs_local_scope(func):
+    """Decorator to mark magic functions which need to local scope to run."""
+    func.needs_local_scope = True
+    return func
+
+#-----------------------------------------------------------------------------
+# Class and method decorators for registering magics
+#-----------------------------------------------------------------------------
+
+def magics_class(cls):
+    """Class decorator for all subclasses of the main Magics class.
+
+    Any class that subclasses Magics *must* also apply this decorator, to
+    ensure that all the methods that have been decorated as line/cell magics
+    get correctly registered in the class instance.  This is necessary because
+    when method decorators run, the class does not exist yet, so they
+    temporarily store their information into a module global.  Application of
+    this class decorator copies that global data to the class instance and
+    clears the global.
+
+    Obviously, this mechanism is not thread-safe, which means that the
+    *creation* of subclasses of Magic should only be done in a single-thread
+    context.  Instantiation of the classes has no restrictions.  Given that
+    these classes are typically created at IPython startup time and before user
+    application code becomes active, in practice this should not pose any
+    problems.
+    """
+    cls.registered = True
+    cls.magics = dict(line = magics['line'],
+                      cell = magics['cell'])
+    magics['line'] = {}
+    magics['cell'] = {}
+    return cls
+
+
+def record_magic(dct, magic_kind, magic_name, func):
+    """Utility function to store a function as a magic of a specific kind.
+
+    Parameters
+    ----------
+    dct : dict
+        A dictionary with 'line' and 'cell' subdicts.
+    magic_kind : str
+        Kind of magic to be stored.
+    magic_name : str
+        Key to store the magic as.
+    func : function
+        Callable object to store.
+    """
+    if magic_kind == 'line_cell':
+        dct['line'][magic_name] = dct['cell'][magic_name] = func
+    else:
+        dct[magic_kind][magic_name] = func
+
+
+def validate_type(magic_kind):
+    """Ensure that the given magic_kind is valid.
+
+    Check that the given magic_kind is one of the accepted spec types (stored
+    in the global `magic_spec`), raise ValueError otherwise.
+    """
+    if magic_kind not in magic_spec:
+        raise ValueError('magic_kind must be one of %s, %s given' %
+                         magic_kinds, magic_kind)
+
+
+# The docstrings for the decorator below will be fairly similar for the two
+# types (method and function), so we generate them here once and reuse the
+# templates below.
+_docstring_template = \
+"""Decorate the given {0} as {1} magic.
+
+The decorator can be used with or without arguments, as follows.
+
+i) without arguments: it will create a {1} magic named as the {0} being
+decorated::
+
+    @deco
+    def foo(...)
+
+will create a {1} magic named `foo`.
+
+ii) with one string argument: which will be used as the actual name of the
+resulting magic::
+
+    @deco('bar')
+    def foo(...)
+
+will create a {1} magic named `bar`.
+
+To register a class magic use ``Interactiveshell.register_magic(class or instance)``.
+"""
+
+# These two are decorator factories.  While they are conceptually very similar,
+# there are enough differences in the details that it's simpler to have them
+# written as completely standalone functions rather than trying to share code
+# and make a single one with convoluted logic.
+
+def _method_magic_marker(magic_kind):
+    """Decorator factory for methods in Magics subclasses.
+    """
+
+    validate_type(magic_kind)
+
+    # This is a closure to capture the magic_kind.  We could also use a class,
+    # but it's overkill for just that one bit of state.
+    def magic_deco(arg):
+        if callable(arg):
+            # "Naked" decorator call (just @foo, no args)
+            func = arg
+            name = func.__name__
+            retval = arg
+            record_magic(magics, magic_kind, name, name)
+        elif isinstance(arg, str):
+            # Decorator called with arguments (@foo('bar'))
+            name = arg
+            def mark(func, *a, **kw):
+                record_magic(magics, magic_kind, name, func.__name__)
+                return func
+            retval = mark
+        else:
+            raise TypeError("Decorator can only be called with "
+                            "string or function")
+        return retval
+
+    # Ensure the resulting decorator has a usable docstring
+    magic_deco.__doc__ = _docstring_template.format('method', magic_kind)
+    return magic_deco
+
+
+def _function_magic_marker(magic_kind):
+    """Decorator factory for standalone functions.
+    """
+    validate_type(magic_kind)
+    
+    # This is a closure to capture the magic_kind.  We could also use a class,
+    # but it's overkill for just that one bit of state.
+    def magic_deco(arg):
+        # Find get_ipython() in the caller's namespace
+        caller = sys._getframe(1)
+        for ns in ['f_locals', 'f_globals', 'f_builtins']:
+            get_ipython = getattr(caller, ns).get('get_ipython')
+            if get_ipython is not None:
+                break
+        else:
+            raise NameError('Decorator can only run in context where '
+                            '`get_ipython` exists')
+
+        ip = get_ipython()
+
+        if callable(arg):
+            # "Naked" decorator call (just @foo, no args)
+            func = arg
+            name = func.__name__
+            ip.register_magic_function(func, magic_kind, name)
+            retval = arg
+        elif isinstance(arg, str):
+            # Decorator called with arguments (@foo('bar'))
+            name = arg
+            def mark(func, *a, **kw):
+                ip.register_magic_function(func, magic_kind, name)
+                return func
+            retval = mark
+        else:
+            raise TypeError("Decorator can only be called with "
+                             "string or function")
+        return retval
+
+    # Ensure the resulting decorator has a usable docstring
+    ds = _docstring_template.format('function', magic_kind)
+
+    ds += dedent("""
+    Note: this decorator can only be used in a context where IPython is already
+    active, so that the `get_ipython()` call succeeds.  You can therefore use
+    it in your startup files loaded after IPython initializes, but *not* in the
+    IPython configuration file itself, which is executed before IPython is
+    fully up and running.  Any file located in the `startup` subdirectory of
+    your configuration profile will be OK in this sense.
+    """)
+    
+    magic_deco.__doc__ = ds
+    return magic_deco
+
+
+MAGIC_NO_VAR_EXPAND_ATTR = "_ipython_magic_no_var_expand"
+MAGIC_OUTPUT_CAN_BE_SILENCED = "_ipython_magic_output_can_be_silenced"
+
+
+def no_var_expand(magic_func):
+    """Mark a magic function as not needing variable expansion
+
+    By default, IPython interprets `{a}` or `$a` in the line passed to magics
+    as variables that should be interpolated from the interactive namespace
+    before passing the line to the magic function.
+    This is not always desirable, e.g. when the magic executes Python code
+    (%timeit, %time, etc.).
+    Decorate magics with `@no_var_expand` to opt-out of variable expansion.
+
+    .. versionadded:: 7.3
+    """
+    setattr(magic_func, MAGIC_NO_VAR_EXPAND_ATTR, True)
+    return magic_func
+
+
+def output_can_be_silenced(magic_func):
+    """Mark a magic function so its output may be silenced.
+
+    The output is silenced if the Python code used as a parameter of
+    the magic ends in a semicolon, not counting a Python comment that can
+    follow it.
+    """
+    setattr(magic_func, MAGIC_OUTPUT_CAN_BE_SILENCED, True)
+    return magic_func
+
+# Create the actual decorators for public use
+
+# These three are used to decorate methods in class definitions
+line_magic = _method_magic_marker('line')
+cell_magic = _method_magic_marker('cell')
+line_cell_magic = _method_magic_marker('line_cell')
+
+# These three decorate standalone functions and perform the decoration
+# immediately.  They can only run where get_ipython() works
+register_line_magic = _function_magic_marker('line')
+register_cell_magic = _function_magic_marker('cell')
+register_line_cell_magic = _function_magic_marker('line_cell')
+
+#-----------------------------------------------------------------------------
+# Core Magic classes
+#-----------------------------------------------------------------------------
+
+class MagicsManager(Configurable):
+    """Object that handles all magic-related functionality for IPython.
+    """
+    # Non-configurable class attributes
+
+    # A two-level dict, first keyed by magic type, then by magic function, and
+    # holding the actual callable object as value.  This is the dict used for
+    # magic function dispatch
+    magics = Dict()
+    lazy_magics = Dict(
+        help="""
+    Mapping from magic names to modules to load.
+
+    This can be used in IPython/IPykernel configuration to declare lazy magics
+    that will only be imported/registered on first use.
+
+    For example::
+
+        c.MagicsManager.lazy_magics = {
+          "my_magic": "slow.to.import",
+          "my_other_magic": "also.slow",
+        }
+
+    On first invocation of `%my_magic`, `%%my_magic`, `%%my_other_magic` or
+    `%%my_other_magic`, the corresponding module will be loaded as an ipython
+    extensions as if you had previously done `%load_ext ipython`.
+
+    Magics names should be without percent(s) as magics can be both cell
+    and line magics.
+
+    Lazy loading happen relatively late in execution process, and
+    complex extensions that manipulate Python/IPython internal state or global state
+    might not support lazy loading.
+    """
+    ).tag(
+        config=True,
+    )
+
+    # A registry of the original objects that we've been given holding magics.
+    registry = Dict()
+
+    shell = Instance('IPython.core.interactiveshell.InteractiveShellABC', allow_none=True)
+
+    auto_magic = Bool(True, help=
+        "Automatically call line magics without requiring explicit % prefix"
+    ).tag(config=True)
+    @observe('auto_magic')
+    def _auto_magic_changed(self, change):
+        self.shell.automagic = change['new']
+    
+    _auto_status = [
+        'Automagic is OFF, % prefix IS needed for line magics.',
+        'Automagic is ON, % prefix IS NOT needed for line magics.']
+
+    user_magics = Instance('IPython.core.magics.UserMagics', allow_none=True)
+
+    def __init__(self, shell=None, config=None, user_magics=None, **traits):
+
+        super(MagicsManager, self).__init__(shell=shell, config=config,
+                                           user_magics=user_magics, **traits)
+        self.magics = dict(line={}, cell={})
+        # Let's add the user_magics to the registry for uniformity, so *all*
+        # registered magic containers can be found there.
+        self.registry[user_magics.__class__.__name__] = user_magics
+
+    def auto_status(self):
+        """Return descriptive string with automagic status."""
+        return self._auto_status[self.auto_magic]
+    
+    def lsmagic(self):
+        """Return a dict of currently available magic functions.
+
+        The return dict has the keys 'line' and 'cell', corresponding to the
+        two types of magics we support.  Each value is a list of names.
+        """
+        return self.magics
+
+    def lsmagic_docs(self, brief=False, missing=''):
+        """Return dict of documentation of magic functions.
+
+        The return dict has the keys 'line' and 'cell', corresponding to the
+        two types of magics we support. Each value is a dict keyed by magic
+        name whose value is the function docstring. If a docstring is
+        unavailable, the value of `missing` is used instead.
+
+        If brief is True, only the first line of each docstring will be returned.
+        """
+        docs = {}
+        for m_type in self.magics:
+            m_docs = {}
+            for m_name, m_func in self.magics[m_type].items():
+                if m_func.__doc__:
+                    if brief:
+                        m_docs[m_name] = m_func.__doc__.split('\n', 1)[0]
+                    else:
+                        m_docs[m_name] = m_func.__doc__.rstrip()
+                else:
+                    m_docs[m_name] = missing
+            docs[m_type] = m_docs
+        return docs
+
+    def register_lazy(self, name: str, fully_qualified_name: str):
+        """
+        Lazily register a magic via an extension.
+
+
+        Parameters
+        ----------
+        name : str
+            Name of the magic you wish to register.
+        fully_qualified_name :
+            Fully qualified name of the module/submodule that should be loaded
+            as an extensions when the magic is first called.
+            It is assumed that loading this extensions will register the given
+            magic.
+        """
+
+        self.lazy_magics[name] = fully_qualified_name
+
+    def register(self, *magic_objects):
+        """Register one or more instances of Magics.
+
+        Take one or more classes or instances of classes that subclass the main
+        `core.Magic` class, and register them with IPython to use the magic
+        functions they provide.  The registration process will then ensure that
+        any methods that have decorated to provide line and/or cell magics will
+        be recognized with the `%x`/`%%x` syntax as a line/cell magic
+        respectively.
+
+        If classes are given, they will be instantiated with the default
+        constructor.  If your classes need a custom constructor, you should
+        instanitate them first and pass the instance.
+
+        The provided arguments can be an arbitrary mix of classes and instances.
+
+        Parameters
+        ----------
+        *magic_objects : one or more classes or instances
+        """
+        # Start by validating them to ensure they have all had their magic
+        # methods registered at the instance level
+        for m in magic_objects:
+            if not m.registered:
+                raise ValueError("Class of magics %r was constructed without "
+                                 "the @register_magics class decorator")
+            if isinstance(m, type):
+                # If we're given an uninstantiated class
+                m = m(shell=self.shell)
+
+            # Now that we have an instance, we can register it and update the
+            # table of callables
+            self.registry[m.__class__.__name__] = m
+            for mtype in magic_kinds:
+                self.magics[mtype].update(m.magics[mtype])
+
+    def register_function(self, func, magic_kind='line', magic_name=None):
+        """Expose a standalone function as magic function for IPython.
+
+        This will create an IPython magic (line, cell or both) from a
+        standalone function.  The functions should have the following
+        signatures:
+
+        * For line magics: `def f(line)`
+        * For cell magics: `def f(line, cell)`
+        * For a function that does both: `def f(line, cell=None)`
+
+        In the latter case, the function will be called with `cell==None` when
+        invoked as `%f`, and with cell as a string when invoked as `%%f`.
+
+        Parameters
+        ----------
+        func : callable
+            Function to be registered as a magic.
+        magic_kind : str
+            Kind of magic, one of 'line', 'cell' or 'line_cell'
+        magic_name : optional str
+            If given, the name the magic will have in the IPython namespace.  By
+            default, the name of the function itself is used.
+        """
+
+        # Create the new method in the user_magics and register it in the
+        # global table
+        validate_type(magic_kind)
+        magic_name = func.__name__ if magic_name is None else magic_name
+        setattr(self.user_magics, magic_name, func)
+        record_magic(self.magics, magic_kind, magic_name, func)
+
+    def register_alias(self, alias_name, magic_name, magic_kind='line', magic_params=None):
+        """Register an alias to a magic function.
+
+        The alias is an instance of :class:`MagicAlias`, which holds the
+        name and kind of the magic it should call. Binding is done at
+        call time, so if the underlying magic function is changed the alias
+        will call the new function.
+
+        Parameters
+        ----------
+        alias_name : str
+            The name of the magic to be registered.
+        magic_name : str
+            The name of an existing magic.
+        magic_kind : str
+            Kind of magic, one of 'line' or 'cell'
+        """
+
+        # `validate_type` is too permissive, as it allows 'line_cell'
+        # which we do not handle.
+        if magic_kind not in magic_kinds:
+            raise ValueError('magic_kind must be one of %s, %s given' %
+                             magic_kinds, magic_kind)
+
+        alias = MagicAlias(self.shell, magic_name, magic_kind, magic_params)
+        setattr(self.user_magics, alias_name, alias)
+        record_magic(self.magics, magic_kind, alias_name, alias)
+
+# Key base class that provides the central functionality for magics.
+
+
+class Magics(Configurable):
+    """Base class for implementing magic functions.
+
+    Shell functions which can be reached as %function_name. All magic
+    functions should accept a string, which they can parse for their own
+    needs. This can make some functions easier to type, eg `%cd ../`
+    vs. `%cd("../")`
+
+    Classes providing magic functions need to subclass this class, and they
+    MUST:
+
+    - Use the method decorators `@line_magic` and `@cell_magic` to decorate
+      individual methods as magic functions, AND
+
+    - Use the class decorator `@magics_class` to ensure that the magic
+      methods are properly registered at the instance level upon instance
+      initialization.
+
+    See :mod:`magic_functions` for examples of actual implementation classes.
+    """
+    # Dict holding all command-line options for each magic.
+    options_table = None
+    # Dict for the mapping of magic names to methods, set by class decorator
+    magics = None
+    # Flag to check that the class decorator was properly applied
+    registered = False
+    # Instance of IPython shell
+    shell = None
+
+    def __init__(self, shell=None, **kwargs):
+        if not(self.__class__.registered):
+            raise ValueError('Magics subclass without registration - '
+                             'did you forget to apply @magics_class?')
+        if shell is not None:
+            if hasattr(shell, 'configurables'):
+                shell.configurables.append(self)
+            if hasattr(shell, 'config'):
+                kwargs.setdefault('parent', shell)
+
+        self.shell = shell
+        self.options_table = {}
+        # The method decorators are run when the instance doesn't exist yet, so
+        # they can only record the names of the methods they are supposed to
+        # grab.  Only now, that the instance exists, can we create the proper
+        # mapping to bound methods.  So we read the info off the original names
+        # table and replace each method name by the actual bound method.
+        # But we mustn't clobber the *class* mapping, in case of multiple instances.
+        class_magics = self.magics
+        self.magics = {}
+        for mtype in magic_kinds:
+            tab = self.magics[mtype] = {}
+            cls_tab = class_magics[mtype]
+            for magic_name, meth_name in cls_tab.items():
+                if isinstance(meth_name, str):
+                    # it's a method name, grab it
+                    tab[magic_name] = getattr(self, meth_name)
+                else:
+                    # it's the real thing
+                    tab[magic_name] = meth_name
+        # Configurable **needs** to be initiated at the end or the config
+        # magics get screwed up.
+        super(Magics, self).__init__(**kwargs)
+
+    def arg_err(self,func):
+        """Print docstring if incorrect arguments were passed"""
+        print('Error in arguments:')
+        print(oinspect.getdoc(func))
+
+    def format_latex(self, strng):
+        """Format a string for latex inclusion."""
+
+        # Characters that need to be escaped for latex:
+        escape_re = re.compile(r'(%|_|\$|#|&)',re.MULTILINE)
+        # Magic command names as headers:
+        cmd_name_re = re.compile(r'^(%s.*?):' % ESC_MAGIC,
+                                 re.MULTILINE)
+        # Magic commands
+        cmd_re = re.compile(r'(?P<cmd>%s.+?\b)(?!\}\}:)' % ESC_MAGIC,
+                            re.MULTILINE)
+        # Paragraph continue
+        par_re = re.compile(r'\\$',re.MULTILINE)
+
+        # The "\n" symbol
+        newline_re = re.compile(r'\\n')
+
+        # Now build the string for output:
+        #strng = cmd_name_re.sub(r'\n\\texttt{\\textsl{\\large \1}}:',strng)
+        strng = cmd_name_re.sub(r'\n\\bigskip\n\\texttt{\\textbf{ \1}}:',
+                                strng)
+        strng = cmd_re.sub(r'\\texttt{\g<cmd>}',strng)
+        strng = par_re.sub(r'\\\\',strng)
+        strng = escape_re.sub(r'\\\1',strng)
+        strng = newline_re.sub(r'\\textbackslash{}n',strng)
+        return strng
+
+    def parse_options(self, arg_str, opt_str, *long_opts, **kw):
+        """Parse options passed to an argument string.
+
+        The interface is similar to that of :func:`getopt.getopt`, but it
+        returns a :class:`~IPython.utils.struct.Struct` with the options as keys
+        and the stripped argument string still as a string.
+
+        arg_str is quoted as a true sys.argv vector by using shlex.split.
+        This allows us to easily expand variables, glob files, quote
+        arguments, etc.
+
+        Parameters
+        ----------
+        arg_str : str
+            The arguments to parse.
+        opt_str : str
+            The options specification.
+        mode : str, default 'string'
+            If given as 'list', the argument string is returned as a list (split
+            on whitespace) instead of a string.
+        list_all : bool, default False
+            Put all option values in lists. Normally only options
+            appearing more than once are put in a list.
+        posix : bool, default True
+            Whether to split the input line in POSIX mode or not, as per the
+            conventions outlined in the :mod:`shlex` module from the standard
+            library.
+        """
+
+        # inject default options at the beginning of the input line
+        caller = sys._getframe(1).f_code.co_name
+        arg_str = '%s %s' % (self.options_table.get(caller,''),arg_str)
+
+        mode = kw.get('mode','string')
+        if mode not in ['string','list']:
+            raise ValueError('incorrect mode given: %s' % mode)
+        # Get options
+        list_all = kw.get('list_all',0)
+        posix = kw.get('posix', os.name == 'posix')
+        strict = kw.get('strict', True)
+
+        preserve_non_opts = kw.get("preserve_non_opts", False)
+        remainder_arg_str = arg_str
+
+        # Check if we have more than one argument to warrant extra processing:
+        odict = {}  # Dictionary with options
+        args = arg_str.split()
+        if len(args) >= 1:
+            # If the list of inputs only has 0 or 1 thing in it, there's no
+            # need to look for options
+            argv = arg_split(arg_str, posix, strict)
+            # Do regular option processing
+            try:
+                opts,args = getopt(argv, opt_str, long_opts)
+            except GetoptError as e:
+                raise UsageError(
+                    '%s ( allowed: "%s" %s)' % (e.msg, opt_str, " ".join(long_opts))
+                ) from e
+            for o, a in opts:
+                if mode == "string" and preserve_non_opts:
+                    # remove option-parts from the original args-string and preserve remaining-part.
+                    # This relies on the arg_split(...) and getopt(...)'s impl spec, that the parsed options are
+                    # returned in the original order.
+                    remainder_arg_str = remainder_arg_str.replace(o, "", 1).replace(
+                        a, "", 1
+                    )
+                if o.startswith("--"):
+                    o = o[2:]
+                else:
+                    o = o[1:]
+                try:
+                    odict[o].append(a)
+                except AttributeError:
+                    odict[o] = [odict[o],a]
+                except KeyError:
+                    if list_all:
+                        odict[o] = [a]
+                    else:
+                        odict[o] = a
+
+        # Prepare opts,args for return
+        opts = Struct(odict)
+        if mode == 'string':
+            if preserve_non_opts:
+                args = remainder_arg_str.lstrip()
+            else:
+                args = " ".join(args)
+
+        return opts,args
+
+    def default_option(self, fn, optstr):
+        """Make an entry in the options_table for fn, with value optstr"""
+
+        if fn not in self.lsmagic():
+            error("%s is not a magic function" % fn)
+        self.options_table[fn] = optstr
+
+
+class MagicAlias(object):
+    """An alias to another magic function.
+
+    An alias is determined by its magic name and magic kind. Lookup
+    is done at call time, so if the underlying magic changes the alias
+    will call the new function.
+
+    Use the :meth:`MagicsManager.register_alias` method or the
+    `%alias_magic` magic function to create and register a new alias.
+    """
+    def __init__(self, shell, magic_name, magic_kind, magic_params=None):
+        self.shell = shell
+        self.magic_name = magic_name
+        self.magic_params = magic_params
+        self.magic_kind = magic_kind
+
+        self.pretty_target = '%s%s' % (magic_escapes[self.magic_kind], self.magic_name)
+        self.__doc__ = "Alias for `%s`." % self.pretty_target
+
+        self._in_call = False
+
+    def __call__(self, *args, **kwargs):
+        """Call the magic alias."""
+        fn = self.shell.find_magic(self.magic_name, self.magic_kind)
+        if fn is None:
+            raise UsageError("Magic `%s` not found." % self.pretty_target)
+
+        # Protect against infinite recursion.
+        if self._in_call:
+            raise UsageError("Infinite recursion detected; "
+                             "magic aliases cannot call themselves.")
+        self._in_call = True
+        try:
+            if self.magic_params:
+                args_list = list(args)
+                args_list[0] = self.magic_params + " " + args[0]
+                args = tuple(args_list)
+            return fn(*args, **kwargs)
+        finally:
+            self._in_call = False