From: Logan Capaldo <logancapaldo@...>
Date: 2005-06-10T10:28:03+09:00
Subject: Re: [SUMMARY] Whiteout (#34)

On 6/9/05, Ara.T.Howard@noaa.gov <Ara.T.Howard@noaa.gov> wrote:
[snip] 
> a hack but:
> 
>    harp:~ > cat fix_my_broken_syntax.rb
>    src = open($0).read
>    src.gsub! %r/([_a-z][_a-zA-Z]*)\+\+/, '((\1+=1;\1 - 1))'
>    eval src
>    exit
> 
> 
>    harp:~ > cat a.rb
>    #!/usr/local/bin/ruby -r./fix_my_broken_syntax.rb
>    n = 41
>    p n++
>    p n
> 
> 
>    harp:~ > ./a.rb
>    41
>    42
> 
> 
> cheers.
[snip]

 I have some suggestions for alternate methods. I haven't actually
tried any of these yet, so take this with a grain of salt.

The more interesting one I think would be to use ParseTree, assuming
it allows (or eventually will) allow you to insert a modified
parsetree back into the interpreter. You could then traverse the tree
and look for items semantically instead of by regexps. There are
disadvantages to this of course. You couldn't add new operators and
such for instance, although I would imagine it would be good for
things like AOP (It also probably would be impossible to implement
whiteout using this method). A related option is to write a parser in
ruby for ruby that emits ParseTree sexps that can once again be
inserted into the interpreter. You could then modify this parser to
add whatever syntax constructs you like (new operators etc.) as long
as they could be mapped onto existing ruby syntax (since this is the
point of source filters usually, I see no problem with that
limitation, any more complicated and its just another language written
in ruby).

The other option to consider is a filter using pipes. Have two files,
one with the filterable source (ie written in latin or whitespace or
whatever) and another with the regexp based transformer, and wrap it
up in a script. eg:

$ cat illegible.rb
#@#@#@# -- ? : 2
dfsdasdasd
$ cat filter.rb
#!/usr/bin/env ruby
class LineNoise
         def transform
               ....
         end
end

x = LineNoise.new

IO.popen("ruby") do |rb|
     File.open("illegible.rb") do |ill|
          ill.each do |line|
             rb.print x.transform(line)
          end
     end
end
$

This gets rid of the eval nastiness but adds its own nastiness (like,
where do I find illegible.rb? etc.).

Just some ideas. Of course we could all write our own languages that
are just ruby with some syntax differences ;)