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@eevee
eevee / weakproperty.py
Last active August 29, 2015 14:02
weakproperty
class WeakProperty:
"""Descriptor that automatically holds onto whatever it contains as a weak
reference. Reading this attribute will never raise `AttributeError`; if
the reference is broken or missing, you'll just get `None`.
The actual weak reference is stored in the object's `__dict__` under the
given name, so this acts as sort of a transparent proxy that lets you
forget you're dealing with weakrefs at all.
Of course, if you try to assign a value that can't be weak referenced,
@gvx
gvx / named.py
Created December 11, 2014 23:28
An alternative namedtuple
from collections import OrderedDict
from inspect import Parameter, signature
from itertools import chain, starmap
from operator import itemgetter
__all__ = ['namedtuple']
dict_property = property(lambda self: OrderedDict(zip(self._fields, self)),
doc='dictionary for instance variables (if defined)')
@henrik
henrik / say_when_real_guards.exs
Created December 31, 2015 16:43
Example of using real guard clauses in your own code with Elixir macros. Inspired by `plug :foo when action in [:create, :update]`. Also see https://gist.github.com/henrik/d21251bcf5d569e16ca9 for "fake" guard clauses that allow any condition/function to be used.
defmodule Lab do
defmacro say({:when, _, [message, condition]}) do
{result, _} = Code.eval_quoted(quote do
case true do
true when unquote(condition) -> true
true -> false
end
end)
if result do
@andytill
andytill / Covering more with unit tests.md
Created May 25, 2015 15:20
Covering more with unit tests

Covering more with unit tests

Unit tests are quick to run, quick to write in bulk, target a small area of code, are not prone to timing issues and other intermittent failures and have excellent reporting tools.

However, actual usage is often prevented by side effects which require resources such as processes, ports and ets tables to exist or will crash the test.

Separating code into pure and impure functions can help and is typically beneficial. It can also harm readability, and even then not enable full coverage using unit testing. For example:

receive_message(Msg) ->
@skippy
skippy / cloud-config.yml
Created December 31, 2014 18:38
modifying fleet metadata (from aws meta-data service) before fleet.service start; this is a proof of concept (but it works!)
#cloud-config
---
coreos:
units:
- name: update-fleet-metadata.service
command: start
content: |-
[Unit]
Description=Update Fleet metadata tag
Before=fleet.service
@kcurtin
kcurtin / ex_unite_case_template.ex
Last active February 26, 2016 16:39
Using case templates to setup your database for integration tests with elixir and ecto.
defmodule DBTransactions do
use ExUnit.CaseTemplate
setup_all do
Ecto.Adapters.SQL.begin_test_transaction(Repo)
on_exit fn ->
Ecto.Adapters.SQL.rollback_test_transaction(Repo)
end
end
(ns react-cljs.core
(:require React))
(declare render)
(defn handle-change [e]
(render {:text (.. e -target -value)}))
(defn render [{:keys [text]}]
(React/renderComponent
@henrik
henrik / say_when.exs
Last active September 7, 2016 09:03
Example of using "guard clauses" in your own code with Elixir macros. Inspired by `plug :foo when action in [:create, :update]`. This implementation accepts any types of conditions, not just the subset allowed in actual guard clauses. But also see https://gist.github.com/henrik/68f136f9916165e0defb for an implementation with real guard clauses.
defmodule Lab do
defmacro say({:when, _, [message, condition]}) do
{result, _} = Code.eval_quoted(condition)
if result do
quote do
IO.puts unquote(message)
end
end
end
@martintrojer
martintrojer / blocking.clj
Last active September 4, 2018 13:36
core.async thoughts
;; ------------------------
(defn- log-time [{:keys [ns name line]} f & args]
(let [start (System/nanoTime)
res (apply f args)
elapsed (quot (- (System/nanoTime) start) 1000)]
(log/debug (format "%s/%s:%s %dus" ns name line elapsed))
res))
(defn enable-timing [var]
@alandipert
alandipert / maptemplate.md
Created January 30, 2013 00:28
ClojureScript macros: kinda, sorta, not really.

ClojureScript macros: kinda, sorta, not really.

ClojureScript does not have a standalone macro system. To write ClojureScript macros, one must write them in Clojure and then refer to them in ClojureScript code. This situation is workable, but at a minimum it forces one to keep ClojureScript code and the macros it invokes in separate files. I miss the locality of regular Clojure macros, so I wrote something called maptemplate that gives me back some of what I miss. The technique may be useful in other scenarios.

Problem

Suppose you're wrapping functionality in another namespace or package so that you can have your own namespace of identically named but otherwise decorated functions:

ClojureScript: