In-line data [was multiple plot lines with plot '-']

[Ethan A M. <sf...@us...>]

Revisiting a discussion from last month...

I had a go at implemented data blocks defined as a "here document".
The patch is on SourceForge 
<https://sourceforge.net/tracker/?func=detail&aid=3534646&group_id=2055&atid=302055>

In brief it adds perl-like syntax

$Mydata << EOD
1 2 3
4 5 ?
7 8 9
# comments or anything else legal in a data file
10 11 12
EOD

stats $Mydata using 3
plot $Mydata using 1:3, $Mydata using 0:2, '' using 1:2



Notes:

- The data block name must begin with a '$'.  This allows the
  named data blocks to be tracked internally using the same code
  as other user-defined variables, but prevents a data block name
  from being used in an expression, function, or other places
  that a normal variable would be accepted.

- The end-of-data marker (EOD in the example) can be any
  arbitrary string of alphanumerics beginning with a letter.
  I'm don't know what advantage this gives over requiring a
  fixed character sequence like EOD, but this seems to be how
  here documents are defined in other programming languages.

- The in-line data is read with no interpretation or processing.
  It is simply stored for later use in a "plot" "splot" or "stats"
  command.

- Any plot command that works with a normal text input file should
  work also with an in-line data block.

- The "show variables" command will report
            $Mydata = <5 line datablock>

- Do you think there needs to be a special command to clear all
  existing datablocks?  Right now the only way to clear one is
  to redefine it as a zero-length block:
  $Mydata << EOD
  EOD

Known problems:

- It doesn't work to include a here document definition inside a
  curly-brace delimited clause.  Not that it should ever be necessary
  to do so, but the program should at least not crash if you try it.

- I didn't look into using a data block as input to "fit".
  Do you think this would be useful?

	- Ethan