OpenEuphoria

Re: Forward Definitions

• Posted by "Carl R. White" <C.R.White at SCM.BRAD.AC.UK> Feb 26, 1999
• 436 views

I've been trying to avoid the language arguments 'cause I always come out
looking bad, but I've got to put in my tuppence here...

It seems that everybody wants routine_id() to work like open() already
does.

When the interpreter starts it creates an inbuilt table/sequence of valid
file handles, StdIn, StdOut and StdErr. Every time open() is called,
another entry is added to the table. On close() the entry is removed, but
this wouldn't apply to routine_id().

AFAICT, all Rob needs to do is add a table for the built-in functions.
e.g. (Using Euphoria pseudocode to represent what the Interpreter would
do, rather than C :) ) :

-- Preparsing declarations

global sequence routine_id_table = {
    PUTS_TOKEN,
    LENGTH_TOKEN,
    SEQUENCE_TOKEN,
    ROUTINE_ID_TOKEN, -- insane concept!
    etc_etc_TOKENS
}

-- Setup for parsing/running Euphoria program

while parsing_program do

    -- Do keyword stuff

    if find(tokenize(keyword), {FUNCTION_TOKEN, PROCEDURE_TOKEN,
                                TYPE_TOKEN})
        name = get_function_name()
        -- Check here to see if it's already defined. Do error stuff.
        routine_id_table = append(routine_id_table, name)
        -- granted this means that the first half of the r_i_t list
        -- is integers, while the second half is strings...
    end if

    -- Do builtin function stuff

    if tokenize(keyword) = ROUTINE_ID_TOKEN then
        name = get_function_parameters(1)
        name = name[1]
        t = tokenize(name)
        if t then
            t = find(t, routine_id_table)
        else
            t = find(name, routine_id_table)
        end if

        t = t - 1 -- this mimics the behaviour of the current routine_id()
                  -- and gives a value in the range -1..maxint

        -- place t in the variable specified before the function call
        -- or whatever...
    end if

    -- Whatever else needs to be done

    program_counter = program_counter + whatever
    if program_counter > length(program) then
        parsing_program = FALSE
    end if

end while

-- Finish up execution/parsing

I admit I've probably taken a rather naive view of how the interpreter
does things, but to me, this seems to work.

It wouldn't even break code, because it still only needs one pass, IMHO it
remains within the Euphorian idiom, and it adds the feature that everyone
wants. Remove the "t = t - 1" line, and some more people are happy, but
not necessarily Rob... ;)

Comments? (/me detects: "You're mad!" etc.)
Carl

--
Carl R White -- Final Year Computer Science at the University of Bradford
E-mail........: cyrek- at -bigfoot.com -- Remove hyphens. Ta :)
URL...........: http://www.bigfoot.com/~cyrek/
Uncrackable...: "19.6A.23.38.52.73.45 25.31.1C 3C.53.44.39.58"