Personally I like to use this function instead of a "try: except:"
because try-except will allow names like __metaclass__.
Remember, setattr(obj, attr_name, value) allows attr_name to be any
valid str().
For example: '!@kdafk11', or '1_1', '1e-20', '0.0', '*one', '\n%%',
etc.
def isvalid_named_reference( astring ):
# "varible name" is really a named_reference
# import string # would be cleaner
valid_first_char =
'_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
valid_rest =
'_0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
# I think it's ok here for the rare type-check
# as unicode named-references are not allowed
if type(astring) is not str: return False
if len(astring) == 0: return False
if astring[0] not in valid_first_char: return False
for c in astring[1:]:
if c not in valid_rest: return False
# Python keywords not allowed as named references (variable names)
for astr in ['and', 'assert', 'break', 'class', 'continue',
'def', 'del', 'elif', 'else', 'except', 'exec',
'finally', 'for', 'from', 'global', 'if',
'import', 'in', 'is', 'lambda', 'not', 'or',
'pass', 'print', 'raise', 'return', 'try',
'while', 'yield',]:
if astring == astr: return False
# valid names but bad idea
if astring == '__builtins__': return None
if astring == '__metaclass__': return None
for astr in dir(__builtins__):
if astring == astr: return None # use None as a warning
# there might be more like __slots__, and other
# module level effecting special names like '__metaclass__'
return True
Also when using dynamically created "varible names" to check if your
objects have an attribute with that name already.
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