Extended example
svn: r12550
This commit is contained in:
Jay McCarthy
parent
bea2297421
commit
daff0abe15
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@ -0,0 +1,4 @@
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<h2>@|title|</h2>
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<p>@|body|</p>
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<h1><a href="@|k-url|">Continue</a></h1>
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16
collects/tests/web-server/template/examples/blog-posts.html
Normal file
16
collects/tests/web-server/template/examples/blog-posts.html
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@ -0,0 +1,16 @@
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@in[p posts]{
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<h2>@(post-title p)</h2>
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<p>@(post-body p)</p>
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<ul>
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@in[c (post-comments p)]{
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<li>@|c|</li>
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}
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</ul>
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}
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<h1>New Post</h1>
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<form action="@|k-url|">
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<input name="title" />
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<input name="body" />
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<input type="submit" />
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</form>
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93
collects/tests/web-server/template/examples/blog-xexpr.ss
Normal file
93
collects/tests/web-server/template/examples/blog-xexpr.ss
Normal file
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@ -0,0 +1,93 @@
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#lang scheme
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(require web-server/servlet
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xml
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web-server/servlet-env)
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(define-struct post (title body comments))
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(define posts
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(list
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(make-post
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"(Y Y) Works: The Why of Y"
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"..."
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(list
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"First post! - A.T."
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"Didn't I write this? - Matthias"))
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(make-post
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"Church and the States"
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"As you may know, I grew up in DC, not technically a state..."
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(list
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"Finally, A Diet That Really Works! As Seen On TV"))))
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(define (template section body)
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`(html
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(head (title "Alonzo's Church: " ,section)
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(style ([type "text/css"])
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,(make-cdata #f #f "
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body {
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margin: 0px;
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padding: 10px;
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}
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#main {
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background: #dddddd;
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}")))
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(body
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(script ([type "text/javascript"])
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,(make-cdata #f #f "
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var gaJsHost = ((\"https:\" == document.location.protocol) ?
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\"https://ssl.\" : \"http://www.\");
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document.write(unescape(\"%3Cscript src='\" + gaJsHost +
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\"google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E\"));
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"))
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(script ([type "text/javascript"])
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,(make-cdata #f #f "
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var pageTracker = _gat._getTracker(\"UA-YYYYYYY-Y\");
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pageTracker._trackPageview();
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"))
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(h1 "Alonzo's Church: " ,section)
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(div ([id "main"])
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,@body))))
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(define (blog-posted title body k-url)
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`((h2 ,title)
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(p ,body)
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(h1 (a ([href ,k-url]) "Continue"))))
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(define (extract-post req)
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(define title (extract-binding/single 'title (request-bindings req)))
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(define body (extract-binding/single 'body (request-bindings req)))
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(set! posts
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(list* (make-post title body empty)
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posts))
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(send/suspend
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(lambda (k-url)
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(template "Posted" (blog-posted title body k-url))))
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(display-posts))
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(define (blog-posts k-url)
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(append
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(apply append
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(for/list ([p posts])
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`((h2 ,(post-title p))
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(p ,(post-body p))
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(ul
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,@(for/list ([c (post-comments p)])
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`(li ,c))))))
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`((h1 "New Post")
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(form ([action ,k-url])
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(input ([name "title"]))
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(input ([name "body"]))
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(input ([type "submit"]))))))
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(define (display-posts)
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(extract-post
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(send/suspend
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(lambda (k-url)
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(template "Posts" (blog-posts k-url))))))
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(define (start req)
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(display-posts))
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(serve/servlet start)
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32
collects/tests/web-server/template/examples/blog.html
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32
collects/tests/web-server/template/examples/blog.html
Normal file
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@ -0,0 +1,32 @@
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<html>
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<head>
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<title>Alonzo's Church: @|section|</title>
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<style type="text/css">
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body {
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margin: 0px;
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padding: 10px;
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}
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#main {
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background: #dddddd;
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}
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</style>
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</head>
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<body>
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<script type="text/javascript">
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var gaJsHost = (("https:" == document.location.protocol) ?
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"https://ssl." : "http://www.");
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document.write(unescape("%3Cscript src='" + gaJsHost +
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"google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
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</script>
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<script type="text/javascript">
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var pageTracker = _gat._getTracker("UA-YYYYYYY-Y");
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pageTracker._trackPageview();
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</script>
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<h1>Alonzo's Church: @|section|</h1>
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<div id="main">
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@body
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</div>
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</body>
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</html>
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46
collects/tests/web-server/template/examples/blog.ss
Normal file
46
collects/tests/web-server/template/examples/blog.ss
Normal file
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@ -0,0 +1,46 @@
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#lang scheme
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(require web-server/templates
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web-server/servlet
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web-server/servlet-env)
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(define-struct post (title body comments))
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(define posts
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(list
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(make-post
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"(Y Y) Works: The Why of Y"
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"..."
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(list
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"First post! - A.T."
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"Didn't I write this? - Matthias"))
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(make-post
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"Church and the States"
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"As you may know, I grew up in DC, not technically a state..."
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(list
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"Finally, A Diet That Really Works! As Seen On TV"))))
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(define (template section body)
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(list TEXT/HTML-MIME-TYPE
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(include-template "blog.html")))
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(define (extract-post req)
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(define title (extract-binding/single 'title (request-bindings req)))
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(define body (extract-binding/single 'body (request-bindings req)))
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(set! posts
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(list* (make-post title body empty)
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posts))
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(send/suspend
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(lambda (k-url)
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(template "Posted" (include-template "blog-posted.html"))))
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(display-posts))
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(define (display-posts)
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(extract-post
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(send/suspend
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(lambda (k-url)
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(template "Posts" (include-template "blog-posts.html"))))))
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(define (start req)
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(display-posts))
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(serve/servlet start)
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@ -2,11 +2,13 @@
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@(require "web-server.ss")
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@(require (for-label web-server/servlet
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web-server/templates
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scheme/promise
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scheme/list
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xml))
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@(define xexpr @tech[#:doc '(lib "xml/xml.scrbl")]{X-expression})
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@(define at-reader-ref @secref[#:doc '(lib "scribblings/scribble/scribble.scrbl")]{reader})
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@(define text-ref @secref[#:doc '(lib "scribblings/scribble/scribble.scrbl")]{preprocessor})
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@title[#:tag "templates"]{Templates}
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@ -15,6 +17,9 @@
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The @web-server provides a powerful Web template system for separating the presentation logic of a Web application
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and enabling non-programmers to contribute to PLT-based Web applications.
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@margin-note{Although all the examples here generate HTML, the template language and the @text-ref it is based on can
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be used to generate any text-based format: C, SQL, form emails, reports, etc.}
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@local-table-of-contents[]
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@section{Static}
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@ -62,8 +67,8 @@ Then
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]
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evaluates to the same content as the static example.
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There is no constraints on the values, the way they are used, or the way they are defined, that are made accessible to the template.
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For example,
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There are no constraints on how the lexical context of the template is populated. For instance, you can built template abstractions
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by wrapping the inclusion of a template in a function:
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@schemeblock[
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(define (fast-template thing)
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(include-template "simple.html"))
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@ -94,18 +99,71 @@ and
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</html>
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}|
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Furthermore, there are no constraints on the Scheme used by templates: they can use macros, structs, continuation marks, threads, etc.
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However, Scheme values that are ultimately returned must be printable by the @text-ref@"."
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For example, consider the following outputs of the
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title line of different calls to @scheme[fast-template]:
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@itemize{
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@item{
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@schemeblock[
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(fast-template 'Templates)
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]
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@verbatim[#:indent 2]|{
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<head><title>Fastest Templates in the West!</title></head>
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}
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@item{
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@schemeblock[
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(fast-template 42)
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]
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@verbatim[#:indent 2]|{
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<head><title>Fastest 42 in the West!</title></head>
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}
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@item{
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@schemeblock[
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(fast-template (list "Noo" "dles"))
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]
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@verbatim[#:indent 2]|{
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<head><title>Fastest Noodles in the West!</title></head>
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}|
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}
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@item{
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@schemeblock[
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(fast-template (lambda () "Thunks"))
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]
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@verbatim[#:indent 2]|{
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<head><title>Fastest Thunks in the West!</title></head>
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}|
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}
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@item{
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@schemeblock[
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(fast-template (delay "Laziness"))
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]
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@verbatim[#:indent 2]|{
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<head><title>Fastest Laziness in the West!</title></head>
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}|
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}
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}
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@section{Gotchas}
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One of the most important things to remember about the @at-reader-ref syntax is that the @"@" symbol must be escaped in content:
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To obtain an @"@" symbol in template output, you must escape the @"@" symbol, because it is the escape character of the @at-reader-ref syntax.
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For example, to obtain:
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@verbatim[#:indent 2]|{
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<html>
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<head><title>Fastest @"@"s in the West!</title></head>
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<body>
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<h1>Bang!</h1>
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<h2>Bang!</h2>
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</body>
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</html>
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<head><title>Fastest @s in the West!</title></head>
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}|
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You must write:
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@verbatim[#:indent 2]|{
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<head><title>Fastest @"@"s in the West!</title></head>
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}|
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as your template: literal @"@"s must be replaced with @"@\"@\"".
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The other gotcha is that since the template is compiled into a Scheme program, only its results will be printed. For example, suppose
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we have the template:
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@ -117,7 +175,7 @@ we have the template:
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</table>
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}|
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If this is included in a lexical context with @scheme[clients] bound to @scheme[(list (cons "Young" "Brigham") (cons "Smith" "Joseph"))],
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If this is included in a lexical context with @scheme[clients] bound to @schemeblock[(list (cons "Young" "Brigham") (cons "Smith" "Joseph"))]
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then the template will be printed as:
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@verbatim[#:indent 2]|{
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<table>
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@ -226,3 +284,217 @@ the template to be unescaped, then create a @scheme[cdata] structure:
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]
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}
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@section{Conversion Example}
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Alonzo Church has been maintaining a blog with PLT Scheme for some years and would like to convert to @schememodname[web-server/templates].
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Here's the code he starts off with:
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@schememod[
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scheme
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(require xml
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web-server/servlet
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web-server/servlet-env)
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(code:comment "He actually Church-encodes them, but we'll use structs.")
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(define-struct post (title body comments))
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(define posts
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(list
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(make-post
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"(Y Y) Works: The Why of Y"
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"..."
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(list
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"First post! - A.T."
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"Didn't I write this? - Matthias"))
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(make-post
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"Church and the States"
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"As you may know, I grew up in DC, not technically a state..."
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(list
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"Finally, A Diet That Really Works! As Seen On TV"))))
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(code:comment "A function that is the generic template for the site")
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(define (template section body)
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`(html
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(head (title "Alonzo's Church: " ,section)
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(style ([type "text/css"])
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(code:comment "CDATA objects were useful for returning raw data")
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,(make-cdata #f #f "\n body {\n margin: 0px;\n padding: 10px;\n }\n\n #main {\n background: #dddddd;\n }")))
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(body
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(script ([type "text/javascript"])
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(code:comment "Which is particularly useful for JavaScript")
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,(make-cdata #f #f "\n var gaJsHost = ((\"https:\" == document.location.protocol) ?\n \"https://ssl.\" : \"http://www.\");\n document.write(unescape(\"%3Cscript src='\" + gaJsHost +\n \"google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E\"));\n"))
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(script ([type "text/javascript"])
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,(make-cdata #f #f "\n var pageTracker = _gat._getTracker(\"UA-YYYYYYY-Y\");\n pageTracker._trackPageview();\n"))
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(h1 "Alonzo's Church: " ,section)
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(div ([id "main"])
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(code:comment "He had to be careful to use splicing here")
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,@body))))
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(define (blog-posted title body k-url)
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`((h2 ,title)
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(p ,body)
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(h1 (a ([href ,k-url]) "Continue"))))
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(define (extract-post req)
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(define binds
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(request-bindings req))
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(define title
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(extract-binding/single 'title binds))
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(define body
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(extract-binding/single 'body binds))
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(set! posts
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(list* (make-post title body empty)
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posts))
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(send/suspend
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(lambda (k-url)
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(template "Posted" (blog-posted title body k-url))))
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(display-posts))
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(define (blog-posts k-url)
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(code:comment "append or splicing is needed")
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(append
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(code:comment "Each element of the list is another list")
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(apply append
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(for/list ([p posts])
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`((h2 ,(post-title p))
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(p ,(post-body p))
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(ul
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,@(for/list ([c (post-comments p)])
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`(li ,c))))))
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`((h1 "New Post")
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(form ([action ,k-url])
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(input ([name "title"]))
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(input ([name "body"]))
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(input ([type "submit"]))))))
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(define (display-posts)
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(extract-post
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(send/suspend
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(lambda (k-url)
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(template "Posts" (blog-posts k-url))))))
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(define (start req)
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(display-posts))
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(serve/servlet start)
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]
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Luckily, Alonzo has great software engineering skills, so he's already separated the presentation logic into the functions
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@scheme[blog-posted], @scheme[blog-posts], and @scheme[template]. Each one of these will turn into a different
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template.
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@filepath{blog.html}:
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@verbatim[#:indent 2]|{
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<html>
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<head>
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<title>Alonzo's Church: @|section|</title>
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<style type="text/css">
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body {
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margin: 0px;
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padding: 10px;
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}
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#main {
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background: #dddddd;
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}
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</style>
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</head>
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<body>
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<script type="text/javascript">
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var gaJsHost = (("https:" == document.location.protocol) ?
|
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"https://ssl." : "http://www.");
|
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document.write(unescape("%3Cscript src='" + gaJsHost +
|
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"google-analytics.com/ga.js'
|
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type='text/javascript'%3E%3C/script%3E"));
|
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</script>
|
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<script type="text/javascript">
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var pageTracker = _gat._getTracker("UA-YYYYYYY-Y");
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pageTracker._trackPageview();
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</script>
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<h1>Alonzo's Church: @|section|</h1>
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<div id="main">
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@body
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</div>
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</body>
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</html>
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}|
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Notice that this part of the presentation is much simpler, because the CSS and JavaScript
|
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can be included verbatim, without resorting to any special escape-escaping patterns.
|
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Similarly, since the @scheme[body] is represented as a string, there is no need to
|
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remember if splicing is necessary.
|
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|
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@filepath{blog-posts.html}:
|
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@verbatim[#:indent 2]|{
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@in[p posts]{
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<h2>@(post-title p)</h2>
|
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<p>@(post-body p)</p>
|
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<ul>
|
||||
@in[c (post-comments p)]{
|
||||
<li>@|c|</li>
|
||||
}
|
||||
</ul>
|
||||
}
|
||||
|
||||
<h1>New Post</h1>
|
||||
<form action="@|k-url|">
|
||||
<input name="title" />
|
||||
<input name="body" />
|
||||
<input type="submit" />
|
||||
</form>
|
||||
}|
|
||||
|
||||
This template is even simpler, because there is no list management whatsoever. The defaults "just work".
|
||||
For completeness, we show the final template:
|
||||
|
||||
@filepath{blog-posted.html}:
|
||||
@verbatim[#:indent 2]|{
|
||||
<h2>@|title|</h2>
|
||||
<p>@|body|</p>
|
||||
|
||||
<h1><a href="@|k-url|">Continue</a></h1>
|
||||
}|
|
||||
|
||||
The code associated with these templates is very simple as well:
|
||||
@schememod[
|
||||
scheme
|
||||
(require web-server/templates
|
||||
web-server/servlet
|
||||
web-server/servlet-env)
|
||||
|
||||
(define-struct post (title body comments))
|
||||
|
||||
(define posts ...)
|
||||
|
||||
(define (template section body)
|
||||
(list TEXT/HTML-MIME-TYPE
|
||||
(include-template "blog.html")))
|
||||
|
||||
(define (extract-post req)
|
||||
(define binds
|
||||
(request-bindings req))
|
||||
(define title
|
||||
(extract-binding/single 'title binds))
|
||||
(define body
|
||||
(extract-binding/single 'body binds))
|
||||
(set! posts
|
||||
(list* (make-post title body empty)
|
||||
posts))
|
||||
(send/suspend
|
||||
(lambda (k-url)
|
||||
(template "Posted" (include-template "blog-posted.html"))))
|
||||
(display-posts))
|
||||
|
||||
(define (display-posts)
|
||||
(extract-post
|
||||
(send/suspend
|
||||
(lambda (k-url)
|
||||
(template "Posts" (include-template "blog-posts.html"))))))
|
||||
|
||||
(define (start req)
|
||||
(display-posts))
|
||||
|
||||
(serve/servlet start)
|
||||
]
|
||||
Loading…
Reference in New Issue
Block a user