# I would like to report three bugs in the
# Language Reference Python 3.4.2

#################################
# bug 1: Typo in parameter_list #
#################################

# In 8.6 the rule for parameter_list should be corrected: The first "|" should be "("

# parameter_list ::= (defparameter ",")*
# | "*" [parameter] ("," defparameter)* ["," "**" parameter]
# | "**" parameter
# | defparameter [","] )

# This rule was correct in 3.3 but has been changed with issue bpo-21439, I guess.

###############################################################################
# bug 2: print(*(1,2),) is allowed according to the syntax - but not accepted #
###############################################################################

# In 6.3.4:
# call ::= primary "(" [argument_list [","] | comprehension] ")"
# argument_list ::= positional_arguments ["," keyword_arguments]
# ["," "*" expression] ["," keyword_arguments]
# ["," "**" expression]
# | keyword_arguments ["," "*" expression]
# ["," keyword_arguments] ["," "**" expression]
# | "*" expression ["," keyword_arguments] ["," "**" expression]
# | "**" expression

# Why is this wrong?
print(1,2,)     # is allowed
print(*(1,2))   # is allowed
#print(*(1,2),) # is allowed according to the syntax - but not accepted

# I guess the trailing comma is only allowed when there is no *-argument
# as it is in the rule for parameter_list

###########################################################
# bug 3: decorator rule allows (aditional) trailing comma #
###########################################################

# In 8.6:
# decorator ::= "@" dotted_name ["(" [parameter_list [","]] ")"] NEWLINE
# parameter_list ::= (defparameter ",")*
# ( "*" [parameter] ("," defparameter)* ["," "**" parameter]
# | "**" parameter
# | defparameter [","] )

# Why is this wrong?
def klammer(klammer_left,klammer_right):
    def klammer_decorator(func):
        def func_wrapper(name):
            return klammer_left + func(name) + klammer_right
        return func_wrapper
    return klammer_decorator

@Klammer("<",">",) # is allowed
#@Klammer("<",">",,) # is allowed according to the syntax - but is not accepted
def get_text(name):
return "Hallo " + name
print(get_text("Uli"))

@Klammer(("<",">")) # is allowed
#@Klammer(("<",">"),) # is allowed according to the syntax - but is not accepted
def get_text(name):
return "Hallo " + name
print(get_text("Uli"))

# I guess the decorator rule might be changed to:
# decorator ::= "@" dotted_name ["(" [parameter_list ] ")"] NEWLINE
# The other appearences of parameter_list have no optional comma.

See also bpo-9232, about adding support for trailing commas in all cases of function calls and definitions.

Bug 1 is still present in 3.5. In 3.6 it is no longer relevant because the documentation was changed for bpo-9232 (allowing trailing commas in function definitions).

Bug 2 is present in 2.7, but is not relevant to 3.5+. Trailing commas are now allowed in function calls, probably thanks to PEP-448, unpacking generalizations.

Bug 3 has been fixed in bpo-27042.

bpo-28978 covers the parameter list syntax (Bug 1 + plus another problem).