Question

It turned out that this conditional block keeps on repeating itself in my code. Any other way to make my life easier? Of course, the body to be executed for a condition differs.

if self.datatype == "string":
    t = "z"
elif self.datatype == "double":
    t = "d"
elif self.datatype == "number":
    t = "i"
elif self.datatype == "blob":
    t = "z"
else:
    raise EntParEx("Unknown datatype" + self.datatype)

……more code using the same conditional

def emit_cpp_def(self):
    s = ""
    e = ""
    if self.datatype == "string":
        s += "static const int " + self.lenvar + " = " + self.length + ";"
        s += "\nchar"
        e += "[" + self.lenvar + " + 2" + "]"
    elif self.datatype == "double":
        s += "double"
    elif self.datatype == "number":
        s += "int"
    elif self.datatype == "blob":
        s += "char*"
    else:
        raise EntParEx("Unknown datatype" + self.datatype)

    s += " " + self.cpp_membername;
    s += e
    s += ";"
    return s;

def emit_cursor_def_code(self):
    if self.datatype == "blob":
        return ""

    ret = "nvl(" + self.db_fieldname + ", "
    #TODO: Add default value loading!
    if self.datatype == "string":
        ret += "\' \'"
    elif self.datatype == "double":
        ret += "-1.0"
    elif self.datatype == "number":
        ret += "-1"
    else:
        raise EntParEx("Unknown datatype" + self.datatype)
    ret += "), "
    return ret

EDIT:
I think what I need is something like running a specific function for each type. Unfortunately I’m not that versed in python. Can that be done? i.e.

switch_datatype(function_string(), function_integer(), ...etc)

Is this worse?

Answer 1

If it’s the exact same conditional, stick it in a method and call it where you need it. Otherwise, define the dictionaries somewhere and use whichever you need.

datatypes = {'string': 'z', 'double': 'd', 'number': 'i', 'blob': 'z'}
t = datatypes[self.datatype]

You may catch the KeyError and raise a domain exception.