Henry Widd henryw374

## rich-already-answered-that.md

      
              1 file
            
          
              33 forks
            
          
              9 comments
            
          
              538 stars
            
          
                reborg
                / rich-already-answered-that.md
            
            
              Last active
              February 23, 2024 13:09
            
              
                A curated collection of answers that Rich gave throughout the history of Clojure
              
          
    Rich Already Answered That!

A list of commonly asked questions, design decisions, reasons why Clojure is the way it is as they were answered directly by Rich (even when from many years ago, those answers are pretty much valid today!).
Feel free to point friends and colleagues here next time they ask (again). Answers are pasted verbatim (I've made small adjustments for readibility, but never changed a sentence) from mailing lists, articles, chats.
How to use:

The link in the table of content jumps at the copy of the answer on this page.
The link on the answer itself points back at the original post.

Table of Content


## clojure-delete-on-close-fileinput-stream.clj
(ns delete-on-close-fileinput-stream)

(defn create-fis [^java.io.File f]
  (proxy [java.io.FileInputStream] [f]
    (close []
      (try
        (proxy-super close)
        (finally
          (.delete f))))))


## tanstack-importmap-demo.js
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>demo</title>
</head>
<body>
<div id="app" style="min-height:100%">
    Hello world!

## transit-connection.cljc
(ns transit-connection
  "Connect time-literals to transit."
  (:require [time-literals.read-write]
            #?(:cljs [java.time :refer [Period
                                        LocalDate
                                        LocalDateTime
                                        ZonedDateTime
                                        OffsetTime
                                        Instant
                                        OffsetDateTime

## kaocha-cljs2-ns-filter.clj
(ns com.widdindustries.kaocha-cljs2-ns-pattern-hook
  "the only way I can find to filter kaocha-cljs2 tests by pattern. see comment block for usage"
  (:require [kaocha.core-ext :as core-ext]
            [kaocha.load :as load]))


(defn ns-filter [plan]
  ;(def plan plan)
  ;(println "About to start loading!")
  (update plan :kaocha.test-plan/tests

## datascript-to-datomic-util.cljs
(ns datascript-to-datomic-util
  (:require [datascript :as d]))

;;;; a utility to help with a datomic-datascript roundtrip process involving:
;;; 1. export some data from a datomic database and transact into a datascript instance.
;;; 2. perform one or more transactions against datascript.
;;; 3. transact the sum of all changes made against datascript back into datomic in a single tx

;;; this namespace contains two public functions:
;;; listen-for-changes: listen to datascript transactions and build up a record of changes

## reflection.clj
(defn invoke-private-method [obj fn-name-string & args]
  (let [m (first (filter (fn [x] (.. x getName (equals fn-name-string)))
                   (.. obj getClass getDeclaredMethods)))]
    (. m (setAccessible true))
    (. m (invoke obj args))))

(defn private-field [obj fn-name-string]
  (let [m (.. obj getClass (getDeclaredField fn-name-string))]
    (. m (setAccessible true))
    (. m (get obj))))

## protocol_proxy.clj
(ns protocol-proxy
  "for when you have an object foo, which satisfies some protocols and you want to make adhoc changes to
  one or more of the protocol methods, but just on foo.

  Can be handy for testing.
  "
  (:refer-clojure :exclude [proxy])
  (:require [clojure.string :as string]))
;(remove-ns 'protocol-proxy)

## deps.edn
{:paths ["."]
 :deps  {time-literals/time-literals {:mvn/version "0.1.5"}
         com.cognitect/transit-clj   {:mvn/version "0.8.319"}
         com.cognitect/transit-cljs  {:mvn/version "0.8.256"}
         }}

## contiguous-spans.cljc
(ns contiguous-spans
  "takes pre-sorted dates and returns contiguous periods contained therein.

  see comment block for demo
  "
  (:require [tick.core :as t]))

(defn contiguous-spans
  "takes pre-sorted dates and returns contiguous periods contained.
  dates a and b are contiguous if a plus span-length is equal to b "
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>demo</title>
	</head>
	<body>
	<div id="app" style="min-height:100%">
	Hello world!
	(ns transit-connection
	"Connect time-literals to transit."
	(:require [time-literals.read-write]
	#?(:cljs [java.time :refer [Period
	LocalDate
	LocalDateTime
	ZonedDateTime
	OffsetTime
	Instant
	OffsetDateTime
	(ns com.widdindustries.kaocha-cljs2-ns-pattern-hook
	"the only way I can find to filter kaocha-cljs2 tests by pattern. see comment block for usage"
	(:require [kaocha.core-ext :as core-ext]
	[kaocha.load :as load]))


	(defn ns-filter [plan]
	;(def plan plan)
	;(println "About to start loading!")
	(update plan :kaocha.test-plan/tests
	(ns datascript-to-datomic-util
	(:require [datascript :as d]))

	;;;; a utility to help with a datomic-datascript roundtrip process involving:
	;;; 1. export some data from a datomic database and transact into a datascript instance.
	;;; 2. perform one or more transactions against datascript.
	;;; 3. transact the sum of all changes made against datascript back into datomic in a single tx

	;;; this namespace contains two public functions:
	;;; listen-for-changes: listen to datascript transactions and build up a record of changes
	(defn invoke-private-method [obj fn-name-string & args]
	(let [m (first (filter (fn [x] (.. x getName (equals fn-name-string)))
	(.. obj getClass getDeclaredMethods)))]
	(. m (setAccessible true))
	(. m (invoke obj args))))

	(defn private-field [obj fn-name-string]
	(let [m (.. obj getClass (getDeclaredField fn-name-string))]
	(. m (setAccessible true))
	(. m (get obj))))
	(ns protocol-proxy
	"for when you have an object foo, which satisfies some protocols and you want to make adhoc changes to
	one or more of the protocol methods, but just on foo.

	Can be handy for testing.
	"
	(:refer-clojure :exclude [proxy])
	(:require [clojure.string :as string]))
	;(remove-ns 'protocol-proxy)
	{:paths ["."]
	:deps {time-literals/time-literals {:mvn/version "0.1.5"}
	com.cognitect/transit-clj {:mvn/version "0.8.319"}
	com.cognitect/transit-cljs {:mvn/version "0.8.256"}
	}}
	(ns contiguous-spans
	"takes pre-sorted dates and returns contiguous periods contained therein.

	see comment block for demo
	"
	(:require [tick.core :as t]))

	(defn contiguous-spans
	"takes pre-sorted dates and returns contiguous periods contained.
	dates a and b are contiguous if a plus span-length is equal to b "