[ruby-list:37961] Re: "".split level

もりきゅうです。
むしろ
p "".split(/\t/,1) # [""]
がおかしくて [] になるべき…

[e-mail] (Yukihiro Matsumoto) wrote:
> 結果を見るとむしろ
> 
>   ruby -e '"".split("\t", 1)
> 
> が[""]を返す方が変で、Perlとの類推から考えるとこれも[]になる
> べきではないかと考えます。

ですか。

Perlで書いてみた:
D:\usr\moriq>type split0.pl
use strict;
#print "<", ((defined "")?"T":"F"), ">\n";
#print "<", ((defined undef)?"T":"F"), ">\n";
sub str_inspect {
        my ($str) = @_;
        (defined $str)?qq{"$str"}:"nil";
}
sub strp {
        my ($str) = @_;
        print str_inspect($str), "\n";
}
sub aryp {
        print "[", join(', ', map {str_inspect $_} @_), "]\n";
}
#aryp ("a",undef,"b");
#aryp ("a","b",undef);
sub test {
        my ($str) = @_;
        print "--- str=";
        strp $str;
                aryp split(/x/, $str);
                my $t = sub {
                        my ($limit) = @_;
                        aryp split(/x/, $str, $limit);
                };
        $t->(0);
        $t->(1);
        $t->(2);
        $t->(3);
        $t->(-1);
}
test("");
test("x");
test("axbxc");

D:\usr\moriq>perl split0.pl
--- str=""
[]
[]
[]
[]
[]
[]
--- str="x"
[]
[]
["x"]
["", ""]
["", ""]
["", ""]
--- str="axbxc"
["a", "b", "c"]
["a", "b", "c"]
["axbxc"]
["a", "bxc"]
["a", "b", "c"]
["a", "b", "c"]

D:\usr\moriq>perl -v

This is perl, v5.8.0 built for MSWin32-x86-multi-thread
...

D:\usr\moriq>type split0.rb
def test(str)
  print "--- str="
  p str
  p str.split(/x/)
  t = proc {|limit| p str.split(/x/,limit) }
  t.call(0)
  t.call(1)
  t.call(2)
  t.call(3)
  t.call(-1)
end
test("")
test("x")
test("axbxc")

D:\usr\moriq>d:\usr\bin\ruby split0.rb
--- str=""
[]
[]
[""]
[]
[]
[]
--- str="x"
[]
[]
["x"]
["", ""]
["", ""]
["", ""]
--- str="axbxc"
["a", "b", "c"]
["a", "b", "c"]
["axbxc"]
["a", "bxc"]
["a", "b", "c"]
["a", "b", "c"]

D:\usr\moriq>d:\usr\bin\ruby -v
ruby 1.8.0 (2003-06-23) [i386-mswin32]

----
YOSHIDA Kazuhiro  [e-mail]  http://www.moriq.com/