[Lispweb] New release CL-EMB 0.3.0 (API CHANGES!)

Stefan Scholl stesch at no-spoon.de
Fri Mar 11 17:26:08 CST 2005


New release CL-EMB 0.3.0

CL-EMB is a library to embed Common Lisp and special template
tags into normal text files. Can be used for dynamically
generated HTML pages.


You can download it from
http://common-lisp.net/project/cl-emb/
or install with ASDF-Install.

CL-USER> (asdf:operate 'asdf:load-op :asdf-install)
CL-USER> (asdf-install:install :cl-emb)


Changes:
- API change: EXECUTE-EMB's optional parameters are now keyword
  parameters. You have to change your calls like this:

  OLD:   (emb:execute-emb "foo" '(:language "Common Lisp"))

  NEW:   (emb:execute-emb "foo" :env '(:language "Common Lisp"))

  See the added keyword :ENV before the plist.

- Generator loops.
  The additional keyword parameter GENERATOR-MAKER to EXECUTE-EMB
  lets you supply a function, which returns a generator function.
  Generator functions are described on
  http://www.cs.northwestern.edu/academics/courses/325/readings/graham/generators.html
  
  Basically these are functions which answer to command codes
  :TEST (==> return true when there's no further data from the
  generator), :GET (==> return current value), :NEXT (==> return
  next value)

  The new template tags @genloop and @endgenloop are used to
  build a loop which uses this generator function. First the
  function supplied to GENERATOR-MAKER is called with the
  corresponding keyword to the parameter of @genloop and the
  value in the plist with this key. ("<% @genloop foo %>" ==>
  first parameter :FOO, second parameter (getf env :foo)).

  The loop itself tests if there are further values for
  iterations by calling the generator function with the command
  :TEST. Then the first value is fetched with :NEXT. (No :GET is
  used at the moment.) The returned values have to be plists.

  A simple example from the README:


CL-USER> (emb:register-emb "test10" "Square root from 1 to <% @var numbers %>: <% @genloop numbers %>sqrt(<% @var number %>) = <% @var sqrt %>  <% @endgenloop %>")
#<CL-EMB::EMB-FUNCTION {581EC765}>
CL-USER> (declare (ignore key))
           (let ((i 1))
             #'(lambda (cmd)
                 (ecase cmd
                   (:test (> i n))
                   (:get `(:number ,i :sqrt ,(sqrt i)))
                   (:next (prog1 `(:number ,i :sqrt ,(sqrt i))
                            (unless (> i n)
                              (incf i))))))))
MAKE-SQRT-1-TO-N-GEN
CL-USER> (emb:execute-emb "test10" :env '(:numbers 10) :generator-maker 'make-sqrt-1-to-n-gen)
"Square root from 1 to 10: sqrt(1) = 1.0  sqrt(2) = 1.4142135  sqrt(3) = 1.7320508  sqrt(4) = 2.0  sqrt(5) = 2.236068  sqrt(6) = 2.4494898  sqrt(7) = 2.6457512  sqrt(8) = 2.828427  sqrt(9) = 3.0  sqrt(10) = 3.1622777  "






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