Re: method_missing is cool (was: are there unit tests for cgi.rb?)

Hello,

At 00:44 24/05/2002 +0900, you wrote:
>Hello,
>
>I think method_missing is not good. because, real error is hidden.
>
>On Thu, May 23, 2002 at 12:20:45PM +0900,
>  Jim Freeze wrote:
>
> > puts a.h1("Title")
> > puts a.a({'href'=>'http://mylink'}) { a.h1 { "Title" } }
> > puts a.a({'href'=>'http://mylink'}) { a.h1 { "Title" } }, a.br
>
>Isn't this enough?
>
>def a(element, attr = {})
>   "<#{element}" + attr.collect{|k,v| %Q< #{k}="#{v}"> }.to_s + ">" +
>   if block_given? then yield.to_s + "</#{element}>" else "" end
>end
>
>puts a(:h1){ "Title" }
>puts a(:a, {'href'=>'http://mylink'}){ a(:h1){ "Title" } }
>puts a(:a, {'href'=>'http://mylink'}){ a(:h1){ "Title" } }, a(:br)
>
>
>--
>Wakou Aoyama  <[e-mail]>

Nature loves diversity. After this minimalist solution, here is the
maximalist one ;-)

Yours,

Jean-Hugues

# hmtl.rb
#   Tools to ease HTML code manipulation
#
# 02/05/23, JHR, creation
#
# (C) See at the end

# This module defines a method .html() that calls a block within which calls,
# to methods whose name is an HTML tag name, generate HTML code.
# Warning: If the includer class wants to redefine method_missing() it must
# do so *before* including this module *or* it must starts the definition with
# "return super if html? method_id", where method_id is the first parameter
# of the new method_missing() definition.
# Warning: For <P> use P(), because p() will call Kernel.p().
module HTML

   unless defined? TAGS
     TAGS = \
     begin
       tags = \
       " A ADDRESS APPLET AREA B BASE BASEFONT BIG BLINK BLOCKQUOTE BODY"\
       " BR CAPTION CENTER CITE CODE DD DIR DIV DL DT EM EMBED FONT FORM 
FRAME"\
       " FRAMESET H1 HEAD HR HTML I ILAYER IMG INPUT ISINDEX KBD KEYGEN LAYER"\
       " LI LINK MAP MENU META MULTICOL NOBR NOEMBED NOFRAMES NOLAYER 
NOSCRIPT"\
       " OBJECT OL OPTION P PARAM PLAINTEXT PRE S SCRIPT SELECT SERVER SMALL"\
       " SPACER SPAN STRIKE STRONG STYLE SUB SUP TABLE TD TEXTAREA TH TITLE 
TR"\
       " TT U UL VAR WBR XMP H2 H3 H4 H5 H6"
       hash = {}
       tags.split( " ").each do | tag |
         hash[tag.downcase().intern()]       = true
         hash[(tag.downcase()+"!").intern()] = "</#{tag.downcase()}>"
       end
       hash[:P] = true
       hash[:P!] = "</P>"
       hash
     end
   end

   # Call a block in a context where methods with name matching an HTML tag
   # name will return an HTML code fragment for that tag.
   def html( &block )
     # An instance variable signals the context. Increment handles nesting.
     if @HTML then @HTML += 1 else @HTML = 1 end
     block.call()
   ensure
     # Exit context by removing the instance variable, unless nested call.
     remove_instance_variable( "@HTML") unless (@HTML -= 1) > 0
   end

   # Check that some method name is an HTML tag name. Also handle xx! where
   # ! means "close tag". Case sensitive, please use lowercase only.
   def HTML::tag?( symb )
     TAGS.include? symb
   end

   # Check if a symbol is an HTML tag name (never is when outside of .html()).
   # Case sensitive, please use lowercase only.
   def html?( symb )
     @HTML and HTML::tag? symb
   end

   # Implement HTML tag generation methods.
   # tag() generates <tag>.
   # tag!() generates </tag>.
   # tag(a) generates <tag>a</tag>.
   # tag(hash) generates <tag k=v k=v ...>.
   # tag(x,y} generates <tag k=v ...>something</tag>, either x or y is a hash.
   # tag() {block} is equivalent to tag( value_of_block ).
   # tag(a) {block} is equivalent to tag( a, value_of_block ).
   def method_missing( id, *args )
     #puts "module HTML method_missing() called for id:#{id}"
     # Be transparent if not inside .html() or not an HTML tag
     return super unless @HTML and TAGS[id]
     #puts "module HTML method_missing() now expand #{id} into HTML tag"
     HTML::tag( id, *args)
   end

   # Do the job, called by method_missing().
   def HTML::tag( id, *args )
     tag = TAGS[id]
     # p "Called for: id=#{id}, args= #{args.inspect()}"
     # Handle close tag
     return tag if tag.kind_of? String
     # Get params, param order is actually irrelevant, we check param type 
later
     p1, p2 = args
     # Potential block becomes first param (and first param becomes second one)
     if block_given? then # blocks computes data
       p1, p2 = yield, p1
     end
     # Params order is irrevelant, type is
     if p1.kind_of? Hash then
       attrs, data = p1, p2
     else
       attrs, data = p2, p1
     end
     attr_str = attrs.nil? ? "" : (attrs.collect do | key, value |
       " #{key.to_s().upcase()}=\"#{value}\""
     end).join()
     # If there are data then we need a closing tag, else we don't
     if data then
       "<#{id}#{attr_str}>#{data.to_s()}</#{id}>"
     else
       "<#{id}#{attr_str}>"
     end
   end

end # module HTML


# This helper class makes it easier to build an HTML page.
class HtmlBuf < Array

   # My redefined method_missing() pushes the HTML code into the array
   def method_missing( id, *args )
     # puts "HtmlBuf's missing_method() called for id:#{id}"
     if HTML::tag? id then
       #puts "HtmlBuf is implementing #{id}"
       self << HTML::tag( id, *args)
     else
       #puts "Not an HTML tag in HtmlBuf's method_missing()"
       super
     end
   end

   # You may create a new object with some initial content, or not.
   def initialize( init_content = nil )
     super()
     if init_content then self.replace( [init_content]) end
   end

   # Make + behave like +=
   def +( stuff )
     self.<<( stuff.to_s())
   end

   # Add content with HTML special characters escaped
   def escape( stuff )
     self.<< CGI.escapeHTML( stuff)
   end

   # Return HTML code, as a String, with some \n now and there.
   def content()
     flatten!()
     join( "\n")
   end

end # class HtmlBuf


class HtmlModuleTest
   include HTML
   def method_missing( id, *args )
     puts "My Test method_missing called for id:#{id}"
     return super if html? id
     puts "My method_missing() calls super"
     super
   end
   def do()
     @name = "item1"
     html do
       puts b( @name )                                       # ok !
       puts a('Google', :href => 'http://www.google.com/')   # ok.
       puts ul(li(@name) + li('item2') + li('item3'))        # ok.
       puts br                                               # single entity
       puts h1 { "Hello" }                                   # with a block
       puts br( :align => "Top")                             # with params
       puts P { {:align => "Top"} }                          # with params 
from block
       puts h1( :color => "#000000")  { "Black" }            # with params 
and block
       puts h1( "White") { {:color => "#FFFFFF"} }           # ... reversed ...
       puts P!                                               # close tag
       puts foo()                                            # NameError or 
NoMethodError
     end
     puts a('Google', 'href' => '"http://www.google.com/"')  # NameError or 
NoMethodError
   end
end
# Please uncomment next line to run the test
#begin HtmlModuleTest.new().do(); rescue Exception => ex; puts ex.message; end

class HtmlBufClassTest
   include HTML
   def do()
     html do
       out = HtmlBuf.new( head( title( "Ruby")))
       out.body
       out.  h1 "Ruby Rules"
       out.  h2
       out<<   "See the numbers:"
       out.  h2!
       out.  table
       out.    tr th( "Year") + th( "Ruby Users")
       out.    tr
       out.      td( "2000")  + td( "10K")
       out.    tr!
       out.    tr
       out.      td( "2001")  . td( "100K")
       out.    tr!
       out.  table!
       out.  << "Future is bright!"
       out.body!
       puts out.content()
       out.foo
     end
   end
end
# Please uncomment next line to run the test
#begin HtmlBufClassTest.new().do(); rescue Exception => ex; puts 
ex.message; end

# ***** BEGIN LICENSE BLOCK *****
# Version: MPL 1.1
#
# The contents of this file are subject to the Mozilla Public License Version
# 1.1 (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
# http://www.mozilla.org/MPL/
#
# Software distributed under the License is distributed on an "AS IS" basis,
# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
# for the specific language governing rights and limitations under the
# License.
#
# The Original Code is The Rever Reversible Reason.
#
# The Initial Developer of the Original Code is
# Jean-Hugues ROBERT (born dec 25 1965 in Nimes, France).
# Portions created by the Initial Developer are Copyright (C) 2002
# the Initial Developer. All Rights Reserved.
#
# Contributor(s):
#
# ***** END LICENSE BLOCK *****


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