mirror of https://github.com/status-im/reagent.git
89 lines
2.9 KiB
Clojure
89 lines
2.9 KiB
Clojure
(ns reagentdemo.news.undodemo
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(:require [reagent.core :as reagent :refer [atom]]
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[reagent.interop :refer-macros [.' .!]]
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[reagent.debug :refer-macros [dbg println]]
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[reagentdemo.syntax :as s]
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[sitetools.core :as tools :refer [link]]
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[reagentdemo.common :as common :refer [demo-component]]
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[todomvc.core :as todomvc]))
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(def url "news/cloact-reagent-undo-demo.html")
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(def title "Cloact becomes Reagent: Undo is trivial")
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(def state todomvc/todos)
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(def undo-list (atom nil))
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(defn undo []
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(let [undos @undo-list]
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(when-let [old (first undos)]
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(reset! state old)
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(reset! undo-list (rest undos)))))
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(defn undo-button []
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(let [n (count @undo-list)]
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[:input {:type "button" :on-click undo
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:disabled (zero? n)
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:value (str "Undo (" n ")")}]))
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(defn todomvc-with-undo []
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(add-watch state ::undo-watcher
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(fn [_ _ old-state _]
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(swap! undo-list conj old-state)))
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[:div
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[undo-button]
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[todomvc/todo-app]])
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(defn undo-demo []
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[demo-component {:comp todomvc-with-undo
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:src (s/src-of [:state :undo-list :undo :save-state
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:undo-button :todomvc-with-undo])}])
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(def undo-demo-cleanup
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(with-meta undo-demo {:component-will-unmount
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(fn []
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(reset! undo-list nil)
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(remove-watch state ::undo-watcher))}))
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(defn main [{:keys [summary]}]
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(let [head title]
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[:div.reagent-demo
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[:h1 [link {:href url} head]]
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[:div.demo-text
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[:h2 "(reset! cloact-name \"Reagent\")"]
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[:p "It turns out that ”Cloact” was a really, really bad
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name. It made some people think about birds’ behinds, in
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possibly unhealthy ways, which even Google suggested they
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should."]
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[:p "The new name is " [:strong "Reagent"] ", which hopefully
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doesn’t bring with it the same disgusting connotations."]
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[:p "The API is otherwise unchanged, so a simple
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search-and-replace should suffice."]
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(if summary
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[link {:href url
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:class 'news-read-more} "Read more"]
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[:div.demo-text
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[:h2 "Undo the easy way"]
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[:p "To celebrate the undoing of the apparently disgusting
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name, here is an example of how easy it is to add undo
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functionality to Reagent components."]
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[:p "It simply saves the old state whenever it changes, and
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restores it when the button is clicked."]
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[:p "The really nice thing about ClojureScript is that not
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only is this easy and safe to do, courtesy of immutable data
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structures, it is also efficient. ClojureScript figures out
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how to represent ”changes” to maps and vectors efficiently,
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so that you won’t have to."]
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[undo-demo-cleanup]])]]))
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(tools/register-page url [main] title)
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