Re: Re: Baffled yet again by CDL

[Sergei Gavrikov <sergei.gavrikov@xxxxxxxxx>]

On Wed, 21 Mar 2012, Grant Edwards wrote:

> On 2012-03-21, Jay Foster <jay@xxxxxxxxxxx> wrote:
> > Use
> >
> >      default_value { "\"Foobar\"" }
> >
> > There are many examples in the eCos repository that do this.
> 
> Thanks. I did find some examples after fixing my grep command.
> 
> I still don't get why it's { "\"Foobar\"" } in a default value and {
> "Foobar" } when a user value.  That doesn't seem intuitive at all.

Hi

Grant, I would explain it so, defalt_value vs user_value is something
like MI (machine interface) vs HI (human interface). Look at the value
of a 'defalt_value' as MI instance (i.e. an expression), but, the value
of a 'user_value' is a user input (an input in configtool, or editing
ecos.ecc config file).  **No wrong with TCL here**. Well, then in C

  #include <stdio.h>
  main()
  {
      const char     *default_value = "\"Foobar\"";       // MI
      char            user_value[256];
      printf("default_value is %s\n", default_value);
      printf("user_value? ");
      fflush(stdout);
      fgets(user_value, sizeof(user_value) - 1, stdin);   // HI
      printf("user_value is %s\n", user_value);
      return (0);
  }


compare

  % ./a.out
  default_value is "Foobar"
  user_value? Baz
  user_value is Baz

and

  % ./a.out
  default_value is "Foobar"
  user_value? "Baz"
  user_value is "Baz"


CDL != TCL. CDL is a huge interface in C++ (~40K lines of code) which
uses TCL for some cases. There are useful comments in these sources

  host/libcdl/cdlcore.cxx
  host/libcdl/value.cxx

by the topic.

Sergei

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