Hi Pieter,
Not using an IDE, a single tool made by a single team, can actually lead to more powerful tools being available. I use the following tools in my work developing tryton modules and python (django+flask) based web apps.
Editor: SublimeText and/or Atom (from Github).
I used Eclipse + PyDev in the past, but I find Eclipse a bit slow on the startup and features like multiple cursors make both Sublime and Atom quite appealing. Both offer a semi-retarded kind of code completion that requires that you still know what you're doing. Code completion in Pydev (Eclipse) is much more mature. But, it requires that you setup Pydev to point to the appropriate python executable that can import Tryton packages/modules.
Debugger: the good ol' pdb. It works.
Revision Control: I prefer git over mercurial. But, tryton is a hg project. I use hg and tortoisehg for when I have to interact with mercurial repositories. Otherwise, I'm using git and and git-cola
Test/Dev Execution Environment: virtualenv is your friend.
Database: I have postgresql installed on my workstation. Is there any other way to do it?
To communicate with postgres, e.g. to create new users or new databases, I just use the command line tools as the postgres user.
e.g.
sudo -i -u postgres
createuser -PRESd trytondev
createdb -E UNICODE -O trytondev trytondev34_test
I hope this helps.
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MM