lsstDebug.py

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#
# LSST Data Management System
# Copyright 2008, 2009, 2010 LSST Corporation.
#
# This product includes software developed by the
# LSST Project (http://www.lsst.org/).
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the LSST License Statement and
# the GNU General Public License along with this program.  If not,
# see <http://www.lsstcorp.org/LegalNotices/>.
#
__all__ = ("Info", "getDebugFrame")
 
 
#
# Define a class to configure debugging information
#
class Info:
    """An object cognisant of debugging parameters appropriate for module
    ``modname``.
 
    Any request for a value will return False unless that value has
    been set, either in the module or as an attribute of this object.
 
    E.g.
 
    .. code-block:: python
 
        import lsstDebug
 
        display = lsstDebug.Info(__name__).display
 
    will set display to `False`, unless display has been set with
 
    .. code-block:: python
 
        lsstDebug.Info(__name__).display = True
 
    Why is this interesting?  Because you can replace `lsstDebug.Info` with
    your own version, e.g.
 
    .. code-block:: python
 
        import lsstDebug
 
        def DebugInfo(name):
            # N.b. lsstDebug.Info(name) would call us recursively
            di = lsstDebug.getInfo(name)
            if name == "foo":
                di.display = dict(repair=1, background=2, calibrate=3)
 
            return di
 
        lsstDebug.Info = DebugInfo
 
    Parameters
    ----------
    modname : `str`
        Module name.
 
    Raises
    ------
    KeyError
        Raised if ``modname`` is not loaded.
    """
    def __init__(self, modname):
        import sys
        self.__dict__["_dict"] = sys.modules[modname].__dict__
        self._modname = modname
 
    def __getattr__(self, what):
        """Return the value of the variable "what" in ``self.__modname``
        if set, else False"""
        return self._dict.get(what, False)
 
    def __setattr__(self, what, value):
        """Set the value of the variable "what" in ``self.__modname``
        to value"""
        self._dict[what] = value
 
 
getInfo = Info
 
 
def getDebugFrame(debugDisplay, name):
    """
    Attempt to extract a frame for displaying a product called ``name``
    from the ``debugDisplay`` variable.
 
    Per the above, an instance of `Info` can return an arbitrary object
    (or nothing) as its ``display`` attribute. It is convenient -- though not
    required -- that it be a dictionary mapping data products to frame
    numbers, as shown in the `lsstDebug.Info` example. Given such a dictionary,
    this function extracts and returns the appropriate frame number. If
    ``debugDisplay`` is not a collection, or if ``name`` is not found within
    it, we return `None`.
 
    Parameters
    ----------
    debugDisplay : `object`
        The contents of ``lsstDebug.Info(__name__).display``.
    name : `str`
        The name of the data product to be displayed.
 
    Returns
    -------
    frame : `int`
        A frame number, or `None`.
    """
    if hasattr(debugDisplay, "__contains__") and name in debugDisplay:
        return debugDisplay[name]
    else:
        return None