Question

I am writing a Python program that generates a C++ program. There are a whole bunch of instances of code like this:

class TestBlock(object):
    def __init__(self, mod, name, casetype, generator):
        self.mod = mod
        self.name = name
        self.casetype = casetype
        self.generator = generator

    def fullname(self):
        return "{mod}.{name}".format(**self.__dict__)

    def write_cases(self, outf):
        outf.write("const {casetype} {mod}_{name}[] = {{\n"
                   .format(**self.__dict__))
        for case in self.generator():
            outf.write("  { " + case + " },\n")
        outf.write("};\n\n")

The "text {subst}".format(**self.__dict__) construction is the only way I have found to make the instance variables of self available as named substitutions, and it’s ugly and I do not like it. I would like to be able to write "text {subst}".format(self); is this possible, and if so, how? I’m aware that "text {0.subst}".format(self) will work out of the box and "text {subst}".format(**self) can be made to work with a few special methods, but both of those still have extra gunk.

Answer 1

You could wrap the functionality in a function:

def fmt(msg, obj):
    return msg.format(**obj.__dict__)

Then:

def fullname(self):
    return fmt("{mod}.{name}", self)