Source files which work with perl, python, and ruby

mnc has asked for the wisdom of the Perl Monks concerning the following question:

Can anyone think of a nicer way to do this?
:) Tnx.

eval('0 and eval(\'def length(x) end\')');
0 and length <<2;
"""   #"
2
BEGIN{ eval('$stdin') ? "" : eval('package _X;use Filter::Simple sub {
 s{^(.*?\n__END_OF_RUBY__[^;]+;)}{do{my $x="$1";$x=~ tr/\n/ /c;$x}}se;
 s{(\n#__END_OF_PERL__.*)}{do{my $x="$1";$x =~ tr/\n/ /c;$x}}se;};
 package main;import _X;'); }
# END OF CRUFT


def hello()
  print "Hi there ruby!\n";
end
hello();


__END_OF_RUBY__ = <<'#__END_OF_PYTHON__';


sub hello {
  print "Hi there perl!\n";
}
hello();


#__END_OF_PERL__
"""  #"


def hello() :
  print "Hi there python!"
hello();


#__END_OF_PYTHON__
[download]

which yields

$ perl -w x.ppr; ruby -w x.ppr; python x.ppr 
Hi there perl!
Hi there ruby!
Hi there python!
[download]

at least with perl 5.6.0, ruby 1.6.4, and python 1.5.2. All rather old.

An afternoon hack.
zSyUK3 zat vendian org

Comment on Source files which work with perl, python, and ruby Select or Download Code

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Re: Source files which work with perl, python, and ruby by sgifford (Prior) on Aug 27, 2003 at 04:00 UTC
This program compiles and runs under all three: `print "Hi there!\n";` [download] results in: `[sgifford@sghome sgifford]$ perl -w /tmp/t91 Hi there! [sgifford@sghome sgifford]$ ruby -w /tmp/t91 Hi there! [sgifford@sghome sgifford]$ python /tmp/t91 Hi there!` [download] `:-)`	[reply] [d/l] [select]
Re2: Source files which work with perl, python, and ruby by dragonchild (Archbishop) on Aug 27, 2003 at 12:51 UTC
I believe the trick was to have the source code auto-detect which compiler was compiling it and do specific behavior as a result. In this case, the different print statements. ------ We are the carpenters and bricklayers of the Information Age. The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6 Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.	[reply]
Re: Source files which work with perl, python, and ruby by BooK (Curate) on Aug 27, 2003 at 12:06 UTC
May I point you to P(erl\|ython), 'nother P(erl\|ython) Hacker or P(ython\|erl) (suck\|rule)s!? I have to admit that I do not know Ruby, alas.	[reply]
Re: Source files which work with perl, python, and ruby by Fletch (Bishop) on Aug 27, 2003 at 02:00 UTC
That's pretty cool, but now you just need to get a trilingual quine . . . :)	[reply]
Re: Source files which work with perl, python, and ruby [webpage] by mnc (Beadle) on Aug 28, 2003 at 16:20 UTC
There is now a webpage for the hack. And `eval('0 and eval(\'def length(x) end\')'); 0 and length <<2;` [download] has been simplified to `0 and eval('false') and length <<2;` [download] Perl and python consider 0 false, so "`0 and`" is a test for ruby. There is no point in ruby actually executing `length`, we just need the heredoc, so we add an always failing test for ruby's `false`. To avoid a perl unquoted string warning, we wrap it in an eval. Which may or may not be faster than ruby actually calling a do nothing "`def length(x) end`" ruby function, but it avoids namespace pollution. The core concept is that the token `length` is serving both as a variable in a bitshift for python, and as a function with a heredoc argument for perl and ruby. The heredoc jumps over pythons `"""` multi-line string token, which the perl parser doesnt like. The name "length" was chosen because perl needs to have seen the function declared in order to parse the line correctly, and `length()` seemed innocuous. So that's the thinking behind this fragment. Still more work to be done. Thanks for the comments.	[reply] [d/l] [select]