instance + classmethod question

[Laszlo Zsolt Nagy]

  Hello,

Is it possible to tell, which instance was used to call the classmethod 
that is currently running?

Background: I have a class called DatabaseConnection and it has a 
classmethod called process_create_tables. This method should create some 
database tables defined by a database definition object. The 
DatabaseConnection has many descendants, for example 
PostgreSQLConnection. Descendants know how to create tables in a given 
RDBMS type. I also use subclasses of the 'SQLProcessor' class, that 
processes SQL commands in different ways (print to stdout, write to 
file, execute directly in the database etc.) I would like to use the 
process_create_tables classmethod as is, because sometimes I only need 
to save a SQL script. However, I also want to use the same classmethod 
to create tables directly into an existing database. That database is 
presented as a DatabaseConnection instance. In that case, I only want to 
create the tables that do not exists yet.  Examples:

processor = SQLProcessors.StdOutProcessor() # Print to stdout
PostgreSQLConnection.process_create_tables(processor,dbdef)  # This 
sould create all tables, using the processor

processor = SQLProcessors.DirectProcessor(conn) # Execute directly
conn.process_create_tables(processor,dbdef) # This should create 
non-existing tables only, using the processor

Is this possible? Maybe there is a better way to achieve this, I'm not 
sure. I was thinking about this construct:

@classsmethod
def process_create_tables(cls,processor,dbdef,conn=None)

and then calling it as

conn.process_create_tables(processor,dbdef,conn)

but this looks very ugly to me. It would be much easier if I could tell 
which instance (if any) was used to call the classmethod.

Thanks,

   Les