Re: THROW codes and ambiguous conditions

Paul Rubin <no.email@nospam.invalid> writes:

I wonder if there's a standard or well known way to capture the output
of . and related words, like redirecting the input stream.

In some systems TYPE and EMIT are a deferred words.  So I can do

: no-output-execute ( ... xt -- ... )
  action-of type action-of emit 2>r
  ['] 2drop is type ['] drop is emit catch
  2r> is emit is type
  throw ;

." |" 5 ' . no-output-execute ." |"

This works in Gforth and in VFX64.

SwiftForth has a system (personalities) for vectoring a number of I/O
words, including TYPE.  So the code above does not work in SwiftForth,
but you can define a personality to achieve the same thing.  LOCATE
SIMPLE-BUFFERING in SwiftForth to see how a personality is defined.

Gforth actually gives you both worlds: TYPE is a defer-flavoured field
in a method table accessed through a user variable.  So you can define
such a table (with OUTPUT:) and use it for changing the output, or you
can do the quick-and-dirty approach of revectoring the individual
words shown above.

However, if you actually want to have the result in a string, you also
need to manage a buffer such that consecutive calls to TYPE and EMIT
are concatenated.  In Gforth, >STRING-EXECUTE does all that for you.
You only have to FREE the buffer once you are done with it.

- anton
--
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
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