Re: [Yaml-core] Embedded YAML

[trans. (T. Onoma) <tra...@ru...>]

On Saturday 08 January 2005 08:45 pm, Rich Morin wrote:
| At 12:51 PM -0500 1/8/05, trans.  (T. Onoma) wrote:
| >I wonder if YAML embedding might deserve some consideration. ...
|
| I doubt that my own use is what you have in mind, but here it is,
| for the record.  I'm using embedded YAML as a machine-readable
| way to document and control the data flow of a substantial suite
| of scripts, control files, etc.

Yes, it is quite different. Nonetheless it is interesting to see others work 
in this area.

| Each hand-edited file contains several lines of embedded YAML.  A
| reference file (eg, foo.yml) would have lines specifying its use.
| A script would have additional lines, specifying input and output
| files, etc.
|
| A harvesting script traverses directories where hand-edited files
| are to be found.  For each file, it:
|
|    *  outputs identifying header comments
|    *  extracts all lines starting with the string "#DDF "
|    *  removes the identifying string from each line
|    *  performs some specialized macro processing
|    *  outputs the resulting YAML code, comments, etc.

You use #DDF to embed the YAML. I wonder if start and end marks would not be 
enough:

    --- !DDF
    - path:     'bin/con_y2d'
      desc:     'create diagrams for Constituent relationships'
      label:    'con_y2d'
      type:     'Perl script'
      inp_g:    |
        a_etc/{con,pkg_use,tag_sum,use_tree}.yml
        e_etc/{def_{con,int},package}.yml
      out_g:    |
        a_cir/*_*_*.{dot,inc,shtml}
        a_con/*_*.{dot,shtml}
        a_pnp/Pack_*_con.inc
      out_m:    'a_etc/exit_con_y2d'
    ...

Though I think a real end-of-document marker is needed (instead of the 
end-of-stream '...').

| The result is a single YAML file, whose content describes the use
| of both hand-edited and machine-generated files.  Other scripts
| use this information to generate dot(1), HTML, and make(1) files.
| In the process, they report on missing or anomalous configuration
| data.  The result of all this is
|
|    *  a documentary web page with image-mapped data flow diagrams
|       for each part of the production system
|
|    *  a run of the production system, using the generated make(1)
|       file
|
| Although Jon Bentley might not approve, this is really one of his
| "little languages".  YAML serves as the fundamental syntax, so I
| don't have to worry about real parsing issues, but the result is
| a declarative data-flow language, of sorts.
|
| Some of the macro processing is quite trivial, though very useful.
| Brace expansion, for example, is stolen from the C-shell:
|
|    label:  '{A,B}_{1,2,3}'
|
| turns into
|
|    label:  'A_1 A_2 A_3 B_1 B_2 B_3'
|
| Some of the other expansions are rather more complex and tied to
| the exact way that the follow-on scripts work.  In all cases, the
| macros help me to type less and (it says here :) reduce mistakes.
|
| For more information, see
|
|    "Introduction to the #DDF Entry Format"
|    
| http://www.slac.stanford.edu/exp/glast/flight/web/e_tut/DDF_format.shtml

Cool. Thanks for sharing.

-T.

P.S. Does the YAML spec speak to YAML in YAML? I don't recall.