[cl-who-devel] Macros for outlining

[Vsevolod Dyomkin]

See this:
http://common-lisp.net/pipermail/cl-who-devel/2010-February/000421.html

Best regards,
Vsevolod

On Sun, Mar 28, 2010 at 11:10 PM, J. K. Cunningham <
J.k.cunningham at comcast.net> wrote:

>  I've been playing around with a way to partially automate writing
> outline-based pages and run into something I don't know how to do. I'm
> hoping someone can perhaps offer a solution or point me in the right
> direction. I've reduced the scope to a fairly simple situation which might
> seem unmotivated in this form. But if I can find a way to do this, the rest
> of what I'm doing will fall into place.
>
> I'd like to be able to write code that looks like this (example):
>
> (let ((hform "A Title"))  (with-html-output (*standard-output* nil :indent 0)    (section (hform)          (:p "A paragraph can go here. ")          (section ("A Subtitle")            "Subsection text goes here."))    (section ("Second Title")      "Any cl-who syntax input here:"      (:ol (:li "Item 1")           (:li "Item 2")))))
>
> where SECTION would be a macro so that it can take CL-WHO syntax arguments.
> The idea is that the SECTION macro would expand so that I ended up
> effectively with this:
>
> (let ((form "A Title"))  (with-html-output (*standard-output* nil :indent 0)    (:h1 (str form))    (:p "A paragraph can go here. ")    (:h2 "A Subtitle")    "Subsection text goes here."    (:h1 "Second Title")    "Any cl-who syntax input here:"    (:ol (:li "Item 1")         (:li "Item 2"))))
>
> I came up with a helper macro like this to handle the levels as a variable:
>
> (defmacro hn (level &body body)  ``(,(intern (format nil "H~d" ,level) :keyword)       ,, at body))
> (let ((lvl 2)      (title "A Title"))  (with-html-output (*standard-output*)    (str (hn lvl (:b (str title))))))
>
> ;; => <h2><b>A Title</b></h2>
>
>
> This enables me to write code that looks like this:
>
> (defmacro section ((n &rest heading) &body body)  `(str (with-html-output-to-string (s nil :indent 0)          (str (hn ,n , at heading))          (str (with-html , at body)))))
> (let ((lvl 1)      (form "A Title"))  (with-html-output (*standard-output* nil :indent 0)    (section (lvl form)          (:p "A paragraph can go here. ")          (section ((1+ lvl) "A Subtitle")            "Subsection text goes here."))    (section (lvl "Second Title")      "Any cl-who syntax input here:"      (:ol (:li "Item 1")           (:li "Item 2")))))
>
>
> But this leaves me with having to manage the levels manually. What I can't
> figure out how to do is write the SECTION macro so it doesn't require the
> LVL arguments, incrementing them recursively.
>
> If it could be written as a function, I could use a closure that started at
> LVL = 1 and incremented at each level, but I'm not good enough with macros
> to see how to do this.
>
> I'm probably looking at this the wrong way. Does anyone have any ideas how to go about this?
>
> Regards,
> Jeff Cunningham
>
>
>
>
>
>
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-- 
vsevolod
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