from UserDict import UserDict
import os, string, sys, types
class WillNotRunError(Exception): pass
class PropertiesObject(UserDict):
"""
A PropertiesObject represents, in a dictionary-like fashion, the values found in a Properties.py file. That file is always included with a Webware component to advertise its name, version, status, etc. Note that a Webware component is a Python package that follows additional conventions. Also, the top level Webware directory contains a Properties.py.
Component properties are often used for:
* generation of documentation
* runtime examination of components, especially prior to loading
PropertiesObject provides additional keys:
* filename - the filename from which the properties were read
* versionString - a nicely printable string of the version
* requiredPyVersionString - like versionString but for requiredPyVersion instead
* willRun - 1 if the component will run. So far that means having the right Python version.
* willNotRunReason - defined only if willRun is 0. contains a readable error message
Using a PropertiesObject is better than investigating the Properties.py file directly, because the rules for determining derived keys and any future convenience methods will all be provided here.
Usage example:
from MiscUtils.PropertiesObject import PropertiesObject
props = PropertiesObject(filename)
for item in props.items():
print '%s: %s' % item
Note: We don't normally suffix a class name with "Object" as we have with this class, however, the name Properties.py is already used in our containing package and all other packages.
"""
## Init and reading ##
def __init__(self, filename=None):
UserDict.__init__(self)
if filename:
self.readFileNamed(filename)
def readFileNamed(self, filename):
self['filename'] = filename
results = {}
exec open(filename) in results
# @@ 2001-01-20 ce: try "...in self"
self.update(results)
self.cleanPrivateItems()
self.createDerivedItems()
## Self utility ##
def cleanPrivateItems(self):
""" Removes items whose keys start with a double underscore, such as __builtins__. """
for key in self.keys():
if key[:2]=='__':
del self[key]
def createDerivedItems(self):
self.createVersionString()
self.createRequiredPyVersionString()
self.createWillRun()
def _versionString(self, version):
""" For a sequence containing version information such as (2, 0, 0, 'pre'), this returns a printable string such as '2.0-pre'. The micro version number is only excluded from the string if it is zero. """
ver = map(lambda x: str(x), version)
if ver[2]=='0': # e.g., if minor version is 0
numbers = ver[:2]
else:
numbers = ver[:3]
rest = ver[3:]
numbers = string.join(numbers, '.')
rest = string.join(rest, '-')
if rest:
return numbers + rest
else:
return numbers
def createVersionString(self):
self['versionString'] = self._versionString(self['version'])
def createRequiredPyVersionString(self):
self['requiredPyVersionString'] = self._versionString(self['requiredPyVersion'])
def createWillRun(self):
self['willRun'] = 0
try:
# Invoke each of the checkFoo() methods
for key in self.willRunKeys():
methodName = 'check' + string.upper(key[0]) + key[1:]
method = getattr(self, methodName)
method()
except WillNotRunError, msg:
self['willNotRunReason'] = msg
return
self['willRun'] = 1 # we passed all the tests
def willRunKeys(self):
""" Returns a list of keys whose values should be examined in order to determine if the component will run. Used by createWillRun(). """
return ['requiredPyVersion', 'requiredOpSys', 'deniedOpSys', 'willRunFunc']
def checkRequiredPyVersion(self):
pyVer = getattr(sys, 'version_info', None)
if not pyVer:
# Prior 2.0 there was no version_info
# So we parse it out of .version which is a string
pyVer = string.split(sys.version)[0]
pyVer = string.split(pyVer, '.')
pyVer = map(lambda x: int(x), pyVer)
if tuple(pyVer)<tuple(self['requiredPyVersion']):
raise WillNotRunError, 'Required python ver is %s, but actual ver is %s.' % (self['requiredPyVersion'], pyVer)
def checkRequiredOpSys(self):
requiredOpSys = self.get('requiredOpSys', None)
if requiredOpSys:
# We accept a string or list of strings
if type(requiredOpSys)==types.StringType:
requiredOpSys = [requiredOpSys]
if not os.name in requiredOpSys:
raise WillNotRunError, 'Required op sys is %s, but actual op sys is %s.' % (requiredOpSys, os.name)
def checkDeniedOpSys(self):
deniedOpSys = self.get('deniedOpSys', None)
if deniedOpSys:
# We accept a string or list of strings
if type(deniedOpSys)==types.StringType:
deniedOpSys = [deniedOpSys]
if os.name in deniedOpSys:
raise WillNotRunError, 'Will not run on op sys %s and actual op sys is %s.' % (deniedOpSys, os.name)
def checkRequiredSoftware(self):
""" Not implemented. No op right now. """
# Check required software
# @@ 2001-01-24 ce: TBD
# Issues include:
# - order of dependencies
# - circular dependencies
# - examining Properties and willRun of dependencies
reqSoft = self.get('requiredSoftware', None)
if reqSoft:
for soft in reqSoft:
# type, name, version
pass
def checkWillRunFunc(self):
willRunFunc = self.get('willRunFunc', None)
if willRunFunc:
whyNotMsg = willRunFunc()
if whyNotMsg:
raise WillNotRunError, whyNotMsg