from opcode import opmap, HAVE_ARGUMENT
globals().update(opmap)
class DataHolder(object):
_varname_ = 'Set'
# This varname `Set` should be treated like a reserved keyword
# and should be used for other purpose at any scope.
def __call__(self, **kwargs):
if len(kwargs) != 1:
raise TypeError(
'%s takes exactly 1 keyword argument (%s given)'%(
self._varname_, len(kwargs)))
name, value = kwargs.popitem()
setattr(self, name, value)
return value
def _support_testassign(f):
co = f.__code__
code = list(co.co_code)
consts = list(co.co_consts)
varnames = list(co.co_varnames)
if consts[-1] is DataHolder: # already applied
return
code.insert(0, LOAD_CONST)
code.insert(1, len(consts) & 0xFF)
code.insert(2, len(consts) >> 8)
code.insert(3, CALL_FUNCTION)
code.insert(4, 0 & 0xFF)
code.insert(5, 0 >> 8)
code.insert(6, STORE_FAST)
code.insert(7, len(varnames) & 0xFF)
code.insert(8, len(varnames) >> 8)
consts.append(DataHolder)
varnames.append(DataHolder._varname_)
i, pos = 0, len(varnames)-1
while i < len(code):
opcode = code[i]
if opcode == LOAD_GLOBAL:
oparg = code[i+1] + (code[i+2] << 8)
name = co.co_names[oparg]
if name == DataHolder._varname_:
code[i] = LOAD_FAST
code[i+1] = pos & 0xFF
code[i+2] = pos >> 8
elif (opcode == CONTINUE_LOOP or
JUMP_IF_FALSE_OR_POP <= opcode <= POP_JUMP_IF_TRUE):
oparg = code[i+1] + (code[i+2] << 8) + 9
code[i+1] = oparg & 0xFF
code[i+2] = oparg >> 8
i += 1
if opcode >= HAVE_ARGUMENT:
i += 2
codeobj = type(co)(co.co_argcount, co.co_kwonlyargcount,
co.co_nlocals+1, co.co_stacksize, co.co_flags,
bytes(code), tuple(consts), co.co_names,
tuple(varnames), co.co_filename, co.co_name,
co.co_firstlineno, co.co_lnotab, co.co_freevars,
co.co_cellvars)
return type(f)(codeobj, f.__globals__, f.__name__, f.__defaults__,
f.__closure__)
def install_testassign(mc):
# mc can be a module or globals() dict
from types import FunctionType
if isinstance(mc, dict):
d = mc
d[DataHolder._varname_] = DataHolder()
else:
try:
d = vars(mc)
except TypeError:
return
for k, v in d.items():
if v in (_support_testassign, install_testassign, DataHolder):
continue
if isinstance(v, FunctionType):
newv = _support_testassign(v)
try:
d[k] = newv
except TypeError:
setattr(mc, k, newv)
elif isinstance(v, type):
try:
setattr(v, DataHolder._varname_, DataHolder())
except Exception:
pass
install_testassign(v)
def test_while(file):
while Set(line=file.readline()):
print(Set.line.rstrip())
def test_recursion(file):
if Set(value=file.readline()):
test_recursion(file)
print(Set.value.rstrip())
def test_nonlocal():
Set(x=100)
def sub():
Set(y=1000)
print('inner function:', getattr(Set, 'x', 'Set has no attribute `x` in this scope'))
print('inner function:', getattr(Set, 'y', 'Set has no attribute `y` in this scope'))
sub()
print('outer function:', getattr(Set, 'x', 'Set has no attribute `x` in this scope'))
print('outer function:', getattr(Set, 'y', 'Set has no attribute `y` in this scope'))
# This should be called after all function and
# class definitions in a module.
install_testassign(globals())
# ---- Begin Test ---------
from io import StringIO
file = StringIO('\n'.join('Line no : %d'%(i+1) for i in range(5)))
print('Testing while statement:')
test_while(file)
print('\nTesting recursion:')
file.seek(0)
test_recursion(file)
print('\nTesting nonlocal scope:')
test_nonlocal()
print('\nTesting module level:')
# Using `Set` in the Module level scope can only
# be done after calling install_testassign.
file.seek(0)
while Set(line=file.readline()):
print(Set.line.rstrip())
Diff to Previous Revision
--- revision 2 2011-12-17 19:23:21
+++ revision 3 2011-12-17 20:03:26
@@ -62,6 +62,7 @@
f.__closure__)
def install_testassign(mc):
+ # mc can be a module or globals() dict
from types import FunctionType
if isinstance(mc, dict):
d = mc
