db.master.uri is wrong

[Cory Johns]

In [10]: rel['db:4'].master.uri
Out[10]: 'postgresql://juju_review-queue:SJGPHw32wws7kmxCPFYnHKKmSYRTYXYW43f2@10.50.12.129:5432/review-queue'

In [11]: rel['db:4'].master.host
Out[11]: '10.50.12.126'

https://git.launchpad.net/interface-pgsql/tree/requires.py#n78 should be "c.uri =" instead of "self.uri =" but I also don't understand why __new__ was used instead of __init__, or even why it's a subclass of str.

[Stuart Bishop (stub)]

It is a subclass of str so it can be used with C extensions that expect a real immutable string without casting (like psycopg2 IIRC). Maybe this isn't the best choice, as I realized the other day you can't do 'conn_str.application_name = 'myname' to modify it.