Prototype error for CMessage.GetParamsColon on Python #958

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2026-10-05T04:55:31+02:00

adam commented

2026-10-05 04:55:31 +02:00

Version: 1.8.1

The API bindings appear unhappy in Python.

Traceback (most recent call last):
  File "/.../modules/blah.py", line 246, in OnPrivCTCPMessage
    self.PutModule("ParamsColon 1: " + str(message.GetParamsColon(1)))
  File "/.../znc/modpython/znc_core.py", line 3588, in GetParamsColon
     return _znc_core.CMessage_GetParamsColon(self, uIdx, uLen)
TypeError: Wrong number or type of arguments for overloaded function 'CMessage_GetParamsColon'.
  Possible C/C++ prototypes are:
    CMessage::GetParamsColon(unsigned int,unsigned int) const
    CMessage::GetParamsColon(unsigned int) const

Relevant lines in /.../znc/modpython/znc_core.py are as follows:

def GetParamsColon(self, uIdx: 'unsigned int', uLen: 'unsigned int'=-1) -> "CString":
    return _znc_core.CMessage_GetParamsColon(self, uIdx, uLen)

Clearly an unsigned int cannot be -1 (why that definition on C++ side anyways?!), so my guess is that some code (SWIG?) chokes on this.

I have tried setting uLen to None in the hope it would fall back to the 1-parameter version, but no dice.

Temporary workaround for anyone who needs the default for that parameter:

import _znc_core
self.PutModule("ParamsColon 1: " + str(_znc_core.CMessage_GetParamsColon(message, 1)))

I don't know what the proper way is to resolve this. Regenerate SWIG? Fix the original class definition with a proper overload somehow? I leave it up to the experts. 😄

**Version**: 1.8.1 The API bindings appear unhappy in Python. ``` Traceback (most recent call last): File "/.../modules/blah.py", line 246, in OnPrivCTCPMessage self.PutModule("ParamsColon 1: " + str(message.GetParamsColon(1))) File "/.../znc/modpython/znc_core.py", line 3588, in GetParamsColon return _znc_core.CMessage_GetParamsColon(self, uIdx, uLen) TypeError: Wrong number or type of arguments for overloaded function 'CMessage_GetParamsColon'. Possible C/C++ prototypes are: CMessage::GetParamsColon(unsigned int,unsigned int) const CMessage::GetParamsColon(unsigned int) const ``` Relevant lines in `/.../znc/modpython/znc_core.py` are as follows: ``` def GetParamsColon(self, uIdx: 'unsigned int', uLen: 'unsigned int'=-1) -> "CString": return _znc_core.CMessage_GetParamsColon(self, uIdx, uLen) ``` Clearly an unsigned int cannot be -1 (why that definition on C++ side anyways?!), so my guess is that some code (SWIG?) chokes on this. I have tried setting `uLen` to None in the hope it would fall back to the 1-parameter version, but no dice. Temporary workaround for anyone who needs the default for that parameter: ``` import _znc_core self.PutModule("ParamsColon 1: " + str(_znc_core.CMessage_GetParamsColon(message, 1))) ``` I don't know what the proper way is to resolve this. Regenerate SWIG? Fix the original class definition with a proper overload somehow? I leave it up to the experts. 😄

adam commented

2026-10-05 04:55:31 +02:00

Can you show your code?

Can you show your code?

adam commented

2026-10-05 04:55:32 +02:00

It is pretty much in the traceback, which is why I didn't post it. It is just a global module, with the hook in it, and the line of the exception.

# paramcolonexample.py

import traceback
import znc

class paramcolonexample(znc.Module):
    description = "Example python3 module that shows broken GetParamColon binding"

    # virtual EModRet CModule::OnPrivCTCPMessage ( CCTCPMessage& Message )
    def OnPrivCTCPMessage(self, message):
        try:
            self.PutModule("Broken binding test!")
            self.PutModule("ParamsColon: " + str(message.GetParamsColon(3)))
        except Exception as ex:
            self.PutModule("An error occurred while executing this command.")
            self.PutModule(''.join(traceback.format_exception(etype=type(ex), value=ex, tb=ex.__traceback__)))
        return znc.CONTINUE

(Edited to add the return statement that is there in my code but forgotten about... but I might as well add it before someone is like 'you should put that in', because it is in there in reality. 😄 )

((And edited a second time because our conversation made me realize that you couldn't see the exception because znc loves swallowing uncaught exceptions.))

It is pretty much in the traceback, which is why I didn't post it. It is just a global module, with the hook in it, and the line of the exception. ```python # paramcolonexample.py import traceback import znc class paramcolonexample(znc.Module): description = "Example python3 module that shows broken GetParamColon binding" # virtual EModRet CModule::OnPrivCTCPMessage ( CCTCPMessage& Message ) def OnPrivCTCPMessage(self, message): try: self.PutModule("Broken binding test!") self.PutModule("ParamsColon: " + str(message.GetParamsColon(3))) except Exception as ex: self.PutModule("An error occurred while executing this command.") self.PutModule(''.join(traceback.format_exception(etype=type(ex), value=ex, tb=ex.__traceback__))) return znc.CONTINUE ``` (Edited to add the return statement that is there in my code but forgotten about... but I might as well add it before someone is like 'you should put that in', because it is in there in reality. 😄 ) ((And edited a second time because our conversation made me realize that you couldn't see the exception because znc loves swallowing uncaught exceptions.))

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Reference: adam/znc#958