Live data from Hacker News

Show HN: Python requirements for Humans

github.com

11–20 of 21 posts

Re: Show HN: Python requirements for Humans

#11
post #10

I see a problem with that "License is MIT". That's not how software is licensed and if the author wants this to be used, the legal part must be flawless. Who's the copyright holder? How can I contact that person? What's the copyright year? Licensing software with MIT licence is trivial: http://choosealicense.com/licenses/mit/ Depending on the project, if I really care about the legal status of the code I use, I may c…

[deleted]

Re: Show HN: Python requirements for Humans

#12
post #10

I see a problem with that "License is MIT". That's not how software is licensed and if the author wants this to be used, the legal part must be flawless. Who's the copyright holder? How can I contact that person? What's the copyright year? Licensing software with MIT licence is trivial: http://choosealicense.com/licenses/mit/ Depending on the project, if I really care about the legal status of the code I use, I may c…

I'll add license file in repository. Thank you.

Re: Show HN: Python requirements for Humans

#13

This is a nice idea in theory, but setup.py and requirements.txt are not the same, and you cannot particularly generate one from the other: https://caremad.io/2013/07/setup-vs-requirement/ Also, unfortunately pip's parser for requirements.txt isn't public, like much of its internals at the moment, which means AIUI it's likely that the parsing code here is going to be brittle if it uses it, or miss edge cases if it do…

As somebody who deploys a lot of business-critical Python apps at $EMPLOYER, I don't even write a requirements.txt.

During development and integration testing, I want to get the latest version of my dependencies that I should be compatible with, so I use SemVer matching (somepackage~=1.2.3) in setup.py.

For deployment, I want to use the exact dependency packages that the code was tested against. So after automated testing is complete, it runs "pip wheel" to build wheels of my package and all its dependencies and put them into a directory, then that is the artefact I use to recreate the package in production. Much more reliable than requirement.txt, since it doesn't assume that PyPI or internet access is available, and it doesn't care if upstream authors silently update packages without changing the version number.

The last scenario is unit-testing, because sometimes tests have extra dependencies the rest of the code doesn't share, like a mock library or other test helper. In theory, these extra things could be put in setup.py's "tests_require" option, but then they'd only be installed if you run tests with "python setup.py test", and they'd also be installed with "easy_install", which is terrible. I'm thinking maybe I should use setuptools' "feature" syntax, so you only get the test dependencies if you install with the [test] feature.

Re: Show HN: Python requirements for Humans

#14

This is a nice idea in theory, but setup.py and requirements.txt are not the same, and you cannot particularly generate one from the other: https://caremad.io/2013/07/setup-vs-requirement/ Also, unfortunately pip's parser for requirements.txt isn't public, like much of its internals at the moment, which means AIUI it's likely that the parsing code here is going to be brittle if it uses it, or miss edge cases if it do…

As somebody who deploys a lot of business-critical Python apps at $EMPLOYER, I don't even write a requirements.txt. During development and integration testing, I want to get the latest version of my dependencies that I should be compatible with, so I use SemVer matching (somepackage~=1.2.3) in setup.py. For deployment, I want to use the exact dependency packages that the code was tested against. So after automated te…

Another way to do this, that you or someone may be interested in, is by using pip-tools.

You write a requirements.in text file where you list libraries by just their name, and then run "pip-compile requirements.in" and it will output a requirements.txt.

It also has a function called "pip-sync" which will then install/update everything in the requirements.txt file.

https://github.com/nvie/pip-tools

Re: Show HN: Python requirements for Humans

#15
Python dependency management is a hard problem, but better than most languages [citation needed]. And `pip` and `setup.py` have emerged over several years, with several influences merged in (remember distutils?).

Honestly, I wish you'd picked a different tag-line though (riffing on `requests` no doubt). Unlike `requests`, your solution only works for a subset of deployment situations, because - as already pointed out - `setup.py` and `requirements.txt` are for different things.

One of the best examples for this I've seen is to use both to deploy to a server with no internet connectivity. For development the dependencies are installed from `setup.py`. Then, before deploying, all dependencies are downloaded via `pip download`. Put the dependencies on the server, finally, use `requirements.txt` with `--no-index` and `--find-links` to install. Definitely an interesting setup, but needs must. Unfortunately, your solution doesn't support `--no-index`, `--find-links` and a few others.

You may want to have a look at tools like `pbr` (Python Build Reasonableness) [1], which has an interesting way of dealing with some hard problems. It also shows how to use `setup_requires` so you don't have to have `requirements.py` hanging around in your repo.

[1] http://docs.openstack.org/developer/pbr/

Re: Show HN: Python requirements for Humans

#16

Python dependency management is a hard problem, but better than most languages [citation needed]. And `pip` and `setup.py` have emerged over several years, with several influences merged in (remember distutils?). Honestly, I wish you'd picked a different tag-line though (riffing on `requests` no doubt). Unlike `requests`, your solution only works for a subset of deployment situations, because - as already pointed out…

Thank you! I definitely need to have a look at `pdr`, it looks very interesting.

`requirements.py` doesn't stand to be "the" universal solution to Python dependency problem. It's more like a sugar syntax for "simple" setups.

Re: Show HN: Python requirements for Humans

#17

Python dependency management is a hard problem, but better than most languages [citation needed]. And `pip` and `setup.py` have emerged over several years, with several influences merged in (remember distutils?). Honestly, I wish you'd picked a different tag-line though (riffing on `requests` no doubt). Unlike `requests`, your solution only works for a subset of deployment situations, because - as already pointed out…

I split my time pretty evenly between the Python and Node ecosystems, and I've found that Python dependency management is extremely poor compared to Node dependency management.

For example, Python's lack of support for nested dependencies means that it can be extremely difficult to use small "utility" libraries like six as subdependencies without running into potential problems from conflicting version requirements from other dependencies.

Additionally, Python's management of different types of dependencies is very weak, specifically with regard to setup.py and requirements.txt. npm has (among other things) very nice explicit concepts of development dependencies and regular dependencies, in addition to application shrink-wraps, which gives library maintainers very easy ways to split out different kinds of dependencies, or lock down all dependencies and subdependencies, using the same set of tools.

While I can say that the current version of pip, especially in conjunction with pip-tools, is significantly better than earlier iterations of Python packaging, I strongly hold that Python packaging is substantially worse than at least one other prominent example.

Re: Show HN: Python requirements for Humans

#18
post #17

Python dependency management is a hard problem, but better than most languages [citation needed]. And `pip` and `setup.py` have emerged over several years, with several influences merged in (remember distutils?). Honestly, I wish you'd picked a different tag-line though (riffing on `requests` no doubt). Unlike `requests`, your solution only works for a subset of deployment situations, because - as already pointed out…

I split my time pretty evenly between the Python and Node ecosystems, and I've found that Python dependency management is extremely poor compared to Node dependency management. For example, Python's lack of support for nested dependencies means that it can be extremely difficult to use small "utility" libraries like six as subdependencies without running into potential problems from conflicting version requirements f…

Node is quite bad - it encourages a proliferation of small libraries and remove the needs to move the versions forward. This, in turn, leads to a wasteland of old, unsecure, dependencies in the long them.

Re: Show HN: Python requirements for Humans

#19
post #17

Python dependency management is a hard problem, but better than most languages [citation needed]. And `pip` and `setup.py` have emerged over several years, with several influences merged in (remember distutils?). Honestly, I wish you'd picked a different tag-line though (riffing on `requests` no doubt). Unlike `requests`, your solution only works for a subset of deployment situations, because - as already pointed out…

I split my time pretty evenly between the Python and Node ecosystems, and I've found that Python dependency management is extremely poor compared to Node dependency management. For example, Python's lack of support for nested dependencies means that it can be extremely difficult to use small "utility" libraries like six as subdependencies without running into potential problems from conflicting version requirements f…

Interesting, I've never hit this and I though I've deployed some fairly complex apps, but you're right of course. The site-packages approach isn't great, and means you pretty much need virtualenv, especially on e.g. Debian where the system Python is really important (I do love virtualenvs, and for a workaround they're pretty solid). Nice to see npm has this pretty much baked in (is my understanding?).

And don't get me started on eggs. I guess the nice thing about Python is that the packaging genuinely seems to be improving year-to-year, although still limited by design decisions and backwards compatibility.

Anyway, thanks for this; I've had a pretty informative morning searching for "npm vs pip". I'm not a Javascript dev, and when I've tried to use it I've struggled with the sheer bloat, even e.g. npm vs bower. Even though I'm a bit jealous of npm now, I'll take pip over package management in the usual enterprise juggernauts (C, C#, Perl or Java) any day!

Re: Show HN: Python requirements for Humans

#20

Python dependency management is a hard problem, but better than most languages [citation needed]. And `pip` and `setup.py` have emerged over several years, with several influences merged in (remember distutils?). Honestly, I wish you'd picked a different tag-line though (riffing on `requests` no doubt). Unlike `requests`, your solution only works for a subset of deployment situations, because - as already pointed out…

Thank you! I definitely need to have a look at `pdr`, it looks very interesting. `requirements.py` doesn't stand to be "the" universal solution to Python dependency problem. It's more like a sugar syntax for "simple" setups.

That's fair. If you could get installation via `setup_requires` to work, so people don't need a (soon to be out-of-date) copy of `requirements.py` in their repo, that'd be a win imo.
Post reply on HN