Show HN: Laboratory, a Python port of GitHub's Scientist library for refactoring (opens in new tab)

(github.com)

153 pointsbuttscicles10y ago13 comments

13 comments

11 comments · 6 top-level

lasdfas10y ago· 2 in thread

I imagine this can only work on getters? How do you use this when code makes state changes?

From Github's Scientist [1]:

Because `enabled?` and `run_if` determine when a candidate runs, it's impossible to guarantee that it will run every time. For this reason, Scientist is only safe for wrapping methods that aren't changing data.

When using Scientist, we've found it most useful to modify both the existing and new systems simultaneously anywhere writes happen, and verify the results at read time with `science`.

[1]: https://github.com/github/scientist/blob/master/README.md#de...

tomtompl10y ago

It only should be used for code which doesn't have side effects. According to original github lib.

jack_jennings10y ago· 2 in thread

Before clicking the link I wondered how this would translate the block-based Ruby API into Python. Using Python's with statement is quite nice here, I think.

The with statement is one of my favorite additions to the language. It's a really flexible syntax to encapsulate control flow, exceptions, necessary cleanup steps… etc. etc.

chronial10y ago

I would argue that python provides even simpler syntax to enable functionality like this.

  @experiment.with(new_function)
  def old_function()
      ...

shoyer10y ago

Agreed -- a decorator seems like a much cleaner way to handle this.

1 more reply

nubs10y ago· 1 in thread

Here's some other ports of Scientist I've come across as well:

PHP

https://github.com/LartTyler/Analyst

Javascript

https://github.com/trello/scientist

https://github.com/Runnable/scientist

https://github.com/jirwin/labrat

taspeotis10y ago

.NET

http://haacked.com/archive/2016/01/20/scientist/

ByteJuggler10y ago

Another Python one: https://github.com/staticshock/scientist.py

agentultra10y ago

Cool! Thanks for the tool!

> Imagine you've implemented a complex caching strategy for some objects in your database and a stale cache is simply not acceptable.

I hope you have a formal specification of that cache. That will help ensure your design is correct in the first place before you even get to running it in code.

I shall be playing with this soon. Cheers!

jonathankoren10y ago

Python? Isn't Python dying? ;) https://news.ycombinator.com/item?id=11100251

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