* "I need to develop against multiple Python versions - various Python 3 versions (3.6, 3.7, 3.8, mostly), PyPy, and occasionally Python 2.7 (less and less often, thankfully)."
* "I work on many projects simultaneously, each with different sets of dependencies, so some sort of virtual environment or isolation is critical."
So sure, there is more than one way to manage a Ruby runtime version, but are there any competitors to Ruby's Bundler? I feel like it's the undisputed champion of Ruby dependency management, working with Rubygems, another unopposed incumbent in its own space, and it never even occurred to me that my language should have more than one of either such tool. Can someone help me understand what drove the Python ecosystem to need more than one dependency manager, ELI5?
I am pretty cloistered as a Ruby developer, but my limited professional experience with other language runtimes tells me that the Ruby "developer environment" experience is really second to none, (change my mind.) Is there any tool which is nearly comparable to Ruby's Pry for Python or other interpreted languages? (I doubt that there is!)
Managing gemsets and multiple versions of Ruby is old-hat.
These days, most productions environments are effectively isolated containers. If your production environment is a container, you probably should develop in a container as well. In that case you don't need much tooling for isolating an application's dependencies from other applications.
The tooling that you need is to build a python application, which means (1) get the dependencies (2) copy over some source code (or invoke the C-compiler if build a C<->Python extension) (3) run tests. Python's builtin setuptools does that fine. It didn't strike me as amazingly simple, but it's not amazingly complex either. pip is essentially a convenience wrapper for setuptools, i.e. pip is to setuptools as apt is to dpkg.
Basically, I believe that because of docker isolation is a irrelevant criterion by which to judge a language/ecosystem.
I'm a developer that supports multiple production applications, and I frequently need to make my development environment as similar to production as possible in order to reproduce a production issue for debugging purposes. I depend on that isolation to be able to do this. My work environment is such that I'm not generally permitted to use containers in production (yet). So it stands to reason through your argument that perhaps I shouldn't use them in development either. It sounds like if I were using Python as well instead of Ruby, I'd be having a much harder time.
Honestly, if I could use containers in dev and prod I would, I truly do believe the grass is greener ;) but I would not sacrifice this marvelous isolation tech, in fact I'd prefer to take RVM with me into docker-land so that I can A-B test Ruby versions within the same container image, and be guaranteed that all my cluster's worker nodes will not have to take extraordinary measures and carry both images in order to ensure the application can boot without a download delay, whenever we have to revert the canary (or whatever other minor potentially reversible lifecycle event would normally trigger a node to need to download a new, expensive base set of image layers all over again.)
This works really well: https://github.com/ms-ati/docker-rvm