#!/usr/bin/env python
"""
bug test
	I tried to keep this as simple as possible.
"""

## as was recommended, I've reread the '4.1 Code blocks, execution frames,
##and namespaces' section. :)

glob = 7
def test_01(f):
	a = 0
	# the weard thing is that the above does not get into the globals of
	#the nested functions below.
	def nested_0(a=a):
		"""a workaround"""
		#no questions here, all is as should be.
		print '\nnested_0:'
		print 'globals           :', globals()
		print "eval('globals()') :", eval('globals()')
		print 'locals            :', locals()
		print "eval('locals()')  :", eval('locals()')
		print 'glob              :', glob
		print "eval('glob')      :", eval('glob')
		print 'a                 :', a
		print "eval('a')         :", eval('a')
	def nested_1():
		"""the bug"""
		#The variable a should be global in relation to nested_1 function,
		#and thus, another way to explicitly 'import' it into the locals
		#would be to declare it global.
		global a
		print '\nnested_1:'
		print 'globals           :', globals()
		print "eval('globals()') :", eval('globals()')
		print 'locals            :', locals()
		print "eval('locals()')  :", eval('locals()')
		print 'glob              :', glob
		print "eval('glob')      :", eval('glob')
		print 'a                 :', a
		print "eval('a')         :", eval('a')
	def nested_2():
		"""the bug"""
		print '\nnested_2:'
		print 'globals           :', globals()
		print "eval('globals()') :", eval('globals()')
		print 'locals            :', locals()
		print "eval('locals()')  :", eval('locals()')
		print 'glob              :', glob
		print "eval('glob')      :", eval('glob')
		print 'a                 :', a							#(1)
		print "eval('a')         :", eval('a')					#(2)
	return eval(f)()

##now, here it is:
# as defined in the section 4.1 of the 'Language Reference':
# +=========================+=================================+======================+
# | Code block type         | Global namespace                | Local namespace      |
# +=========================+=================================+======================+
# | Function body           | global n.s. of containing block | new n.s.             |
# +-------------------------+---------------------------------+----------------------+
# | String passed to eval() | global n.s. of caller           | local n.s. of caller |
# +=========================+=================================+======================+
# from the above it is clear that:
#    a. variable a is nether in the globals nor the locals of the
#       function nested_2.
#    b. if variable a is to be printed in (1), it would indicate that
#       it MUST be in a visible namespace, either local or global,
#       thus complying to scoping rules.
# from a and b:
#    only one of the following MUST be correct:
#      - (1) should raise a 'NameError' exception.				(3)
#      - (2) should be equivalent to (1),
#                        and print tha value of a.	            (4)
#
# judging from the fact that in (1) variable a is printed, it MUST
#be in a namespace, and (3) can not be correct.
#
# thus what we have is the 'gap' between the locals and the globals
#of nested functions. (and this most likely is the problem.)
#and it is unclear how and where in (1) the variable a is found, to
#conflict with the Python Language Documentation. 
#


if __name__ == '__main__':
	#the first is a typical demo of nested scopes.
	test_01('nested_0')
	#test_01('nested_1')
	test_01('nested_2')
	
# vim:set ts=4 sw=4 :