win32com Cannot Handle Decimal In COM Objects

[suresafe]

Attempting to makepy for a COM object which has parameters of type Decimal [i.e. .NET Decimal] fails with an error "NameError: name 'Decimal' is not defined"

C:\Python36\Lib\site-packages\win32com\client>makepy
Generating to C:\Python36\lib\site-packages\win32com\gen_py\DFD995C9-8BA8-46A0-A794-D445C13227AEx0x1x1.py
Building definitions from type library...
Generating...
Importing module
Traceback (most recent call last):
  File "C:\Python36\Lib\site-packages\win32com\client\makepy.py", line 387, in <module>
    rc = main()
  File "C:\Python36\Lib\site-packages\win32com\client\makepy.py", line 380, in main
    GenerateFromTypeLibSpec(arg, f, verboseLevel = verboseLevel, bForDemand = bForDemand, BuildHidden = hiddenSpec)
  File "C:\Python36\Lib\site-packages\win32com\client\makepy.py", line 286, in GenerateFromTypeLibSpec
    gencache.AddModuleToCache(info.clsid, info.lcid, info.major, info.minor)
  File "C:\Python36\lib\site-packages\win32com\client\gencache.py", line 548, in AddModuleToCache
    mod = _GetModule(fname)
  File "C:\Python36\lib\site-packages\win32com\client\gencache.py", line 627, in _GetModule
    mod = __import__(mod_name)
  File "C:\Python36\lib\site-packages\win32com\gen_py\DFD995C9-8BA8-46A0-A794-D445C13227AEx0x1x1.py", line 2587, in <module>
    class PurchaseOrderHeader(DispatchBaseClass):
  File "C:\Python36\lib\site-packages\win32com\gen_py\DFD995C9-8BA8-46A0-A794-D445C13227AEx0x1x1.py", line 2595, in PurchaseOrderHeader
    def AddPurchaseOrderProductLine(self, ProductCode_=defaultNamedNotOptArg, QuantityOrdered_=defaultNamedNotOptArg, description_='', UnitPurchasePrice_=Decimal('-1')
NameError: name 'Decimal' is not defined

[suresafe]

Error can be overcome with 1 change to genpy.py (win32com/client)

Add after line 848

    print('from decimal import Decimal', file=self.file)

Additional checking will need done on the specific COM object I have to see if it operates correctly.

[mhammond]

Thanks for the report - please let me if you testing shows that is the only change needed.

[suresafe]

I'm still testing to be sure, but so far this does seem to work.

I also found an interesting comment at http://docs.activestate.com/activepython/3.2/pywin32/html/com/win32com/readme.htm under "Important Currency changes"

Up until build 212, code could set pythoncom.future_currency = True to force use of the decimal module, with a warning issued otherwise. In builds 213 and later, the decimal module is unconditionally used when pythoncon returns you a currency value.

Python 2.3 does not ship with a decimal module. For this reason, win32com/decimal_23.py is supplied with pywin32. This is a clone of the decimal module, but will only be used when import decimal fails. If you want to use this functionality in your Python 2.3 programs, you should write something similar to:

try:
import decimal
except ImportError:
import win32com.decimal_23 as decimal
val = decimal.Decimal("123.45")

[junkmd]

I have probably encountered the same kind of problem.

Traceback (most recent call last):
  File "C:\hostedtoolcache\windows\Python\3.10.11\x64\lib\site-packages\win32com\client\gencache.py", line 261, in GetModuleForCLSID
    __import__(sub_mod_name)
ModuleNotFoundError: No module named 'win32com.gen_py.6BAA1C79-4BA0-47F2-9AD7-D2FFB1C0F3E3x0x1x0.DTestDispServer'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:\a\comtypes\comtypes\comtypes\test\test_dispinterface.py", line 36, in test_win32com_ensure_dispatch
    d = EnsureDispatch("TestDispServerLib.TestDispServer")
  File "C:\hostedtoolcache\windows\Python\3.10.11\x64\lib\site-packages\win32com\client\gencache.py", line 636, in EnsureDispatch
    GetModuleForCLSID(disp_clsid)
  File "C:\hostedtoolcache\windows\Python\3.10.11\x64\lib\site-packages\win32com\client\gencache.py", line 270, in GetModuleForCLSID
    makepy.GenerateChildFromTypeLibSpec(sub_mod, info)
  File "C:\hostedtoolcache\windows\Python\3.10.11\x64\lib\site-packages\win32com\client\makepy.py", line 374, in GenerateChildFromTypeLibSpec
    __import__("win32com.gen_py." + dir_name + "." + child)
  File "C:\Users\RUNNER~1\AppData\Local\Temp\gen_py\3.10\6BAA1C79-4BA0-47F2-9AD7-D2FFB1C0F3E3x0x1x0\DTestDispServer.py", line 28, in <module>
    class DTestDispServer(DispatchBaseClass):
  File "C:\Users\RUNNER~1\AppData\Local\Temp\gen_py\3.10\6BAA1C79-4BA0-47F2-9AD7-D2FFB1C0F3E3x0x1x0\DTestDispServer.py", line 48, in DTestDispServer
    def do_cy(self, value=Decimal('32.78')):
NameError: name 'Decimal' is not defined

Please refer to this for the reproducer: enthought/comtypes#693 (comment)