Python script generating a Python script - evaluation of generated code

Question

I have the following code

def SetSnmpOid(oid, snmpDataType, value):
    try:
        global SNMP_COMMUNITY
        global SNMP_HOST
        global SNMP_PORT

        cmdGen = cmdgen.CommandGenerator()

        # Send to first Telnet IP address, different port for SNMP
        dataType = "rfc1902." + snmpDataType
        errorIndication, errorStatus, errorIndex, varBinds = cmdGen.setCmd(
                cmdgen.CommunityData(SNMP_COMMUNITY, mpModel=0),
                cmdgen.UdpTransportTarget((SNMP_HOST, SNMP_PORT)), 
                                           (oid + "." + str(0), dataType(value)))

which, when run, generates this error

File "H:/code/test_script.txt.py", line 105, in SetSnmpOid
    (oid + "." + str(0), dataType(value)))
TypeError: 'str' object is not callable

and I'm certain that the error refers to dataType (which evaluates to rfc1902.integer, which is correct). The problem seems to be using it as a function call dataType(value) as part of a tuple.

If anyone is interested, I am trying to emulate the code found here.

score 1 · Accepted Answer · edited May 23 '17 at 11:59

This looks like an issue with trying dynamically build a reference to a function.

You're wanting to create a rfc1902.integer object which gets passed as an argument to the cmdgen.UdpTransportTarget. The problem is, the value of dataType is a string, not a callable. Once all the code is evaluated, you end up with this:

'rfc1902.integer'(value)

when what you really want is this:

rfc1902.integer(value)

To get the callable, you have two options

load it using getattr
load it using a dict "switch statement."

Python script generating a Python script - evaluation of generated code

1 Answers1