Flo: Unterschied zwischen den Versionen

Version vom 2. März 2010, 21:50 Uhr

Wir weisen darauf hin, dass möglicherweise nicht alle Beiträge den Anforderungen genügen. Die Anforderungen sind: Flos sind in Liste "flo" gespeichert, zur Ausführ- oder Compilierzeit werden durch den Code einzelne flo0, flo1, flo2, flo3 Variablen angelegt, die später dann auch zur Ausgabe verwendet werden.

 Wir sind die Flo, Widerstand ist zwecklos!

Beiträge, die die Anforderungen erfüllen

#!/usr/bin/env ruby

flo = [ "dividuum", "syb", "fiji", "flowhase" ]

# flos sind keine arrayss1!
for i in 0..flo.size-1
  eval "flo#{i} = flo[#{i}]"
  puts "flo#{i} == \"" + eval("flo#{i}") + "\""
end

Dieses Perl (*duck*) kann ja keiner lesen!¹⁾ Daher:

(eval-when (:compile-toplevel :load-toplevel :execute)
  (defvar *flo-sequence* #("dividuum" "syb" "fiji" "flowhase")))

(defmacro make-individual-flo-variables ()
  (cons 'progn
        (loop for flo across *flo-sequence*
              for i from 0
              collect `(defvar ,(read-from-string (format nil "*flo~d*" i)) ,flo))))

(make-individual-flo-variables)

(dotimes (i 4)
    (format t "~&flo~d = ~a" i (eval (read-from-string (format nil "*flo~d*" i)))))

Dreckiges C:

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
const int flolen = 4;
static char *flos[] = {"dividuum","syb","fiji","flowhase"};
static char *proghead = "#include <stdio.h>\nint main(void){\n";
static char *progend =  "  return(0);\n}\n";
int main(void){
        int i; FILE *o;
        o=fopen("flo2.c","w");
        fputs(proghead,o);
        for(i=0;i<flolen;i++){
                fprintf(o,"  char *flo%d = \"%s\";\n",i,flos[i]);
                fprintf(o,"  printf(\"flo%%d ist %%s\\n\",%d,flo%d);\n",i,i); }
        fputs(progend,o);
        fclose(o);
        system("/usr/bin/gcc -o flos flo2.c;./flos;rm -f flo2.c flos");
        return(0);
}

Nu aber wirklich noch in Perl:

#!/usr/bin/perl

@flo = ( "dividuum", "syb", "fiji", "flowhase" );

for $i (0..$#flo) {
  eval "\$flo$i = \$flo\[$i\]";
  print "\$flo$i eq \"" . eval("\$flo$i") . "\"\n";
}

Gute alte Bash:

#!/bin/sh

flo="dividuum syb fiji flowhase"

n=0
for f in $flo
do
  eval flo$n=$f
  echo -n "flo$n == "
  eval echo \$flo$n
  n=$(($n+1))
done

Realisiert in PHP, Lisp, Perl, XML, Bash und XSLT und immernoch kürzer als die C-Version:

<?php
$flo = array( "dividuum", "syb", "fiji", "flowhase" );

$l = fopen("flo.lisp", "w"); $p = fopen("flo.pl", "w");
fwrite($l, '(progn (format t "~a" "<flo>")');
fwrite($p,'
print <<EOF
  <xsl:stylesheet version="1.0"
                  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                  xmlns="http://www.w3.org/TR/xhtml1/strict">
  <xsl:template match="/">');
    for($i=0;$i<count($flo);$i++) {
      fwrite($l, "(format t \"~a~a~a\" \"<flo$i>\" \"$flo[$i]\" \"</flo$i>\")");
      fwrite($p, "flo$i == <xsl:value-of select=\"flo/flo$i\"/>\n");
    }
    fwrite($l, '(format t "~a" "</flo>"))');
    fwrite($p,'
  </xsl:template>
  </xsl:stylesheet>
EOF'."\n");
fclose($l); fclose($p);
system("sbcl --noinform --load flo.lisp --eval '(quit)' > flo.xml");
system("perl flo.pl > flo.xslt");
system("xsltproc flo.xslt flo.xml | grep -v xml");
?>

http://static.php.net/www.php.net/images/news/php-logo.gif http://www.mail-archive.com/copenhagen@perl.org/msg00162/logo_mermaid.png

Noch einmal in Ruby:

#!/usr/bin/env ruby

flo = [ "dividuum", "syb", "fiji", "flowhase" ]

# flos sind keine arrayss1!
flo.each_with_index do | f, i |
  instance_variable_set "@flo#{i}", f
  puts "flo#{i} = #{instance_variable_get "@flo#{i}"}"
end

'cause JavaScript rocks:

flo = new Array("dividuum", "syb", "fiji", "flowhase");
for (i in flo) {
  eval("flo"+i+" = flo["+i+"]");
  dump("flo"+i+" == "+eval("flo"+i)+"\n");
}

Wir moegen Lua:

#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>

lua_State *L;

char *flos[] = {"dividuum", "syb", "fiji", "flowhase", "florolf"};
char buf[1024];

void main() {
        char *p;
        int i;

        L = luaL_newstate();
        luaL_openlibs(L);

        for(i=0; i < 5; i++) {
                sprintf(buf, "flo%d", i);
                lua_pushstring(L, flos[i]);
                lua_setglobal(L, buf);
        }

        p=buf;
        for(i=0; i < 5; i++)
                p += sprintf(p, "print(\"flo%d = \" .. flo%d);", i, i);

        luaL_dostring(L, buf);
}

Bloatiger Angebercode, der auch noch etwas völlig anderes macht

Und nochmal das, was das Ruby-Programm "mit viel bloatigem Metaprogramming-Foo" macht, allerdings wiederum in Common Lisp gegossen:
(Warnung: (Zumindest) als Lispprogramm ist dieses Beispiel ziemlich unsinning, und z.B. die PRINT-OBJECT-Methode widerspricht der gängigen Konvention.)

(defclass flo ()
  ((name :initarg :name :reader flo-name)
   (skill :initarg :skill :reader flo-skill)
   (notebook :initarg :notebook :reader flo-notebook)))

(defun slot-value-or-something (object &key (slot 'name) (something "without name"))
  (if (slot-boundp object slot)
      (slot-value object slot)
      something))

(defmethod print-object ((flo flo) stream)
  (format stream "~&~a is actually ~a and is good at ~a.~&He loves hacking on his ~a."
          (class-name (class-of flo))
          (slot-value-or-something flo)
          (slot-value-or-something flo :slot 'skill    :something "nothing")
          (slot-value-or-something flo :slot 'notebook :something "dulcimer")))

(defmacro def-flo-class (class-name &key name skill notebook)
  (macrolet ((make-slot-def (name)
               `(when ,name
                  `(,',name :initform ,,name))))
  `(defclass ,class-name (flo)
     ,(remove nil (list
                   (make-slot-def name)
                   (make-slot-def skill)
                   (make-slot-def notebook))))))

(def-flo-class |Flo0|
    :name "dividuum"
    :skill "DOOM"
    :notebook "old Dell")

(def-flo-class |Flo1|
    :name "Peter"
    :skill "math"
    :notebook "IBM Thinkpad")

(def-flo-class |Flo2|
    :name "Fiji"
    :skill "WOW"
    :notebook "I-have-no-idea")

(def-flo-class |Flo3|
    :name "flohase"
    :skill "hoppeln"
    :notebook "hasIbook")

(let ((flos (list (make-instance '|Flo0|)
                  (make-instance '|Flo1|)
                  (make-instance '|Flo2|)
                  (make-instance '|Flo3|))))
  (dolist (flo flos)
    (print flo)))

Ru^W Objektorientiertes C

// Das aendern:
#include "/usr/local/lib/ruby/1.8/i386-freebsd5/ruby.h"

VALUE flo_init(VALUE self)
{
        char *flo[] = {"dividuum", "syb", "fiji", "flowhase"};
        int i;

        for(i = 0; i < 4; i++)
        {
                char varname[6];
                sprintf(varname, "@flo%i", i);  // Insecure!
                rb_iv_set(self, varname, rb_str_new2(flo[i]));
        }
}

VALUE flo_each(VALUE self)
{
        int i;
        VALUE vars = rb_funcall(self, rb_intern("instance_variables"), 0);
        VALUE varname = rb_ary_shift(vars);

        while(varname != Qnil)
        {
                rb_yield(rb_ary_new3(2, varname, rb_iv_get(self, RSTRING(varname)->ptr)));
                varname = rb_ary_shift(vars);
        }

        return(Qnil);
}

int main()
{
        VALUE flo;

        ruby_init();

        flo = rb_define_class("Flo", rb_cObject);
        rb_define_method(flo, "initialize", flo_init, 0);
        rb_define_method(flo, "each", flo_each, 0);

        rb_eval_string("Flo.new.each { |name,value| puts \"#{name.gsub(/^@/, '')} = #{value}\" }");

        return(0);
}

Fußnoten

1) Anmerkung zu: "Dieses Perl (*duck*) kann ja keiner lesen!"

Stimmt doch gar nicht! Ist ganz einfach:

map printf("%s = %s\n", [flo0..flo3]->[$_], [dividuum, syb, fiji, flowhase]->[$_]), 0..$#{@{[flo0..flo3]}};

(Kommentar von mgr: Genau, "0..$#{@{[flo0..flo3]}}" ... q.e.d. Danke für das gute Beispiel. Aber ernsthaft, es ging hier eben gerade *nicht* um Einzeiler, die will niemand.)

Und auch in python kann man Einzeiler schreiben:

print "\n".join(["%s = %s" % (k, v) for k, v in {"flo0":"dividuum", "flo1":"syb", "flo2":"fiji", "flo3":"flowhase"}.items()])