wxWidgets/wxPython/wxversion/wxversion.py

#----------------------------------------------------------------------
# Name:        wxversion
# Purpose:     Allows a wxPython program to search for alternate 
#              installations of the wxPython packages and modify sys.path
#              so they will be found when "import wx" is done.
#
# Author:      Robin Dunn
#
# Created:     24-Sept-2004
# RCS-ID:      $Id$
# Copyright:   (c) 2004 by Total Control Software
# Licence:     wxWindows license
#----------------------------------------------------------------------

"""
If you have more than one version of wxPython installed this module
allows your application to choose which version of wxPython will be
imported when it does 'import wx'.  You use it like this:

    import wxversion
    wxversion.require('2.4')
    import wx

Of course the default wxPython version can also be controlled by
setting PYTHONPATH or by editing the wx.pth path configuration file,
but using wxversion will allow an application to manage the version
selection itself rather than depend on the user to setup the
environment correctly.

It works by searching the sys.path for directories matching wx-* and
then comparing them to what was passed to the require function.  If a
match is found then that path is inserted into sys.path.
"""

import sys, os, glob, fnmatch


_selected = None
class wxversionError(Exception):
    pass


def require(versions):
    """
    Search for a wxPython installation that matches version.

        :param version: Specifies the version to look for, it can
                        either be a string or a list of strings.  Each
                        string is compared to the installed wxPythons
                        and the best match is inserted into the
                        sys.path, allowing an 'import wx' to find that
                        version.

                        The version string is composed of the dotted
                        version number (at least 2 of the 4 components)
                        optionally followed by hyphen ('-') separated
                        options (wx port, unicode/ansi, flavour, etc.)  A
                        match is determined by how much of the installed
                        version matches what is given in the version
                        parameter.  If the version number components don't
                        match then the score is zero, otherwise the score
                        is increased for every specified optional component
                        that is specified and that matches.
    """
    bestMatch = None
    bestScore = 0
    if type(versions) == str:
        versions = [versions]

    global _selected
    if _selected is not None:
        # A version was previously selected, ensure that it matches
        # this new request
        for ver in versions:
            if _selected.Score(_wxPackageInfo(ver)) > 0:
                return
        # otherwise, raise an exception
        raise wxversionError("A previously selected wx version does not match the new request.")

    # If we get here then this is the first time wxversion is used.
    # Ensure that wxPython hasn't been imported yet.
    if sys.modules.has_key('wx') or sys.modules.has_key('wxPython'):
        raise wxversionError("wxversion.require() must be called before wxPython is imported")

    # Look for a matching version and manipulate the sys.path as
    # needed to allow it to be imported.
    packages = _find_installed()
    for pkg in packages:
        for ver in versions:
            score = pkg.Score(_wxPackageInfo(ver))
            if score > bestScore:
                bestMatch = pkg
                bestScore = score

    if bestMatch is None:
        raise wxversionError("Requested version of wxPython not found")

    sys.path.insert(0, bestMatch.pathname)
    _selected = bestMatch
        


_pattern = "wx-[0-9].*"
def _find_installed():
    installed = []
    toRemove = []
    for pth in sys.path:

        # empty means to look in the current dir
        if not pth:
            pth = '.'

        # skip it if it's not a package dir
        if not os.path.isdir(pth):
            continue
        
        base = os.path.basename(pth)

        # if it's a wx path that's already in the sys.path then mark
        # it for removal and then skip it
        if fnmatch.fnmatchcase(base, _pattern):
            toRemove.append(pth)
            continue

        # now look in the dir for matching subdirs
        for name in glob.glob(os.path.join(pth, _pattern)):
            # make sure it's a directory
            if not os.path.isdir(name):
                continue
            # and has a wx subdir
            if not os.path.exists(os.path.join(name, 'wx')):
                continue
            installed.append(_wxPackageInfo(name, True))

    for rem in toRemove:
        del sys.path[sys.path.index(rem)]
        
    installed.sort()
    installed.reverse()
    return installed


class _wxPackageInfo(object):
    def __init__(self, pathname, stripFirst=False):
        self.pathname = pathname
        base = os.path.basename(pathname)
        segments = base.split('-')
        if stripFirst:
            segments = segments[1:]
        self.version = tuple([int(x) for x in segments[0].split('.')])
        self.options = segments[1:]


    def Score(self, other):
        score = 0
        # whatever version components given in other must match exactly
        if len(self.version) > len(other.version):
            v = self.version[:len(other.version)]
        else:
            v = self.version
        if v != other.version:
            return 0
        score += 1
        for opt in other.options:
            if opt in self.options:
                score += 1
        return score
    

    # TODO: factor self.options into the sort order?
    def __lt__(self, other):
        return self.version < other.version
    def __gt__(self, other):
        return self.version > other.version
    def __eq__(self, other):
        return self.version == other.version
        
    



if __name__ == '__main__':
    import pprint
    def test(version):
        # setup
        savepath = sys.path[:]

        #test
        require(version)
        print "Asked for %s:\t got: %s" % (version, sys.path[0])
        #pprint.pprint(sys.path)
        #print

        # reset
        sys.path = savepath[:]
        global _selected
        _selected = None
        
        
    # make some test dirs
    names = ['wx-2.4',
             'wx-2.5.2',
             'wx-2.5.2.9-gtk2-unicode',
             'wx-2.5.2.9-gtk-ansi',
             'wx-2.5.1',
             'wx-2.5.2.8-gtk2-unicode',
             'wx-2.5.3']
    for name in names:
        d = os.path.join('/tmp', name)
        os.mkdir(d)
        os.mkdir(os.path.join(d, 'wx'))

    # setup sys.path to see those dirs
    sys.path.append('/tmp')
    

    # now run some tests
    test("2.4")
    test("2.5")
    test("2.5-gtk2")
    test("2.5.2")
    test("2.5-ansi")
    test("2.5-unicode")
    
    # There isn't a unicode match for this one, but it will give the best
    # available 2.4.  Should it give an error instead?  I don't think so...
    test("2.4-unicode") 

    # Try asking for multiple versions
    test(["2.6", "2.5.3", "2.5.2-gtk2"])

    try:
        # expecting an error on this one
        test("2.6")
    except wxversionError, e:
        print "Asked for 2.6:\t got Exception:", e 

    # check for exception when incompatible versions are requested
    try:
        require("2.4")
        require("2.5")
    except wxversionError, e:
        print "Asked for incompatible versions, got Exception:", e 

    # cleanup
    for name in names:
        d = os.path.join('/tmp', name)
        os.rmdir(os.path.join(d, 'wx'))
        os.rmdir(d)