optparse object population

[Peter Otten]

Eric O. Angell wrote:

> Is there a way to coerce optparse into populating an object for me?

If you are dealing with just one object you can provide a custom values
parameter:

<code>
import optparse

class Header(object):
    def __init__(self):
            self.foo = "default-foo"
            self.bar = "default-bar"
    def __str__(self):
        values = ["%s=%r" % nv for nv in self.__dict__.items()]
        return "%s(%s)" % (self.__class__.__name__, ", ".join(values))
    __repr__ = __str__

p = optparse.OptionParser()
p.add_option("--foo")
p.add_option("--bar")
p.add_option("--baz")

header = Header()
options, args = p.parse_args(["--foo", "custom-foo", "--baz", "custom-baz"],
    values=header)
print "options is header", options is header
# True
print "header", header
</code>

You can even expand that to work with nested objects, but it gets a little
messy and you are probably better off with Jeff Epler's approach here:

<code-continued>
# (insert above code here)

class Header2(Header):
    def __setattr__(self, name, value):
        if "." in name:
            left, right = name.split(".", 1)
            setattr(getattr(self, left), right, value)
        else:
            object.__setattr__(self, name, value)

header2 = Header2()
header2.nested = Header2() # I use the same class here because I'm 
                           # lazy, not for technical reasons
p.add_option("--nested.foo")
options, args = p.parse_args(["--nested.foo", "hi there"], values=header2)
print options
</code-continued>

Especially, I have some doubts whether __setattr__("dotted.name", value)
will always be allowed.

Peter