Fun with v-strings ( or version-0-rama )

[David Weinrich]

After the meeting this week, I decided to do a little reading up on vstrings.
They have now been promoted from 'slightly odd' to 'really really weird' in my
book. Here is a quick program that tests conversion to/from vstrings ( using
version strings from the CVS $Revision:$ tag ). It looks like line 33 is a 
fairly consistent way to convert versions as strings to v-strings.

David Weinrich


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#!/usr/bin/perl -w

# Test to see how strings/numbers are converted to vstrings:
#
# A number that has no '.' ( 1 ) remains a string...
# A number that has one '.' ( 1.1 ) remains a string...
# A number that has more than one '.' is converted to a v-string
@versions = ( 1, 1.1, 1.1.1,  11.0.1, 10.0.0, 11.0.2 );

# Prints out the two strings as their numeric ascii values ( 1 = 49, . = 46 )
# The rest were converted to vstrings and sort/print as expected
foreach $v ( sort @versions ) {
  printf "Version: %vd\n", $v;
}

# Stolen in part from Simon Cozens in the p5p roundup for 8/27/2001
# with another part stolen from the last SDPM meeting
$vstring = join '', map chr, split (/[.]/, qw$Revision: 1.11.1$[1]);
printf "Hex:     %vx\n", $vstring;
printf "Decimal: %vd\n", $vstring;
printf "Octal:   %vo\n", $vstring;
printf "Binary:  %vb\n", $vstring;

# Hrm, can we get the numbers out directly with an unpack?
@parts = unpack "U*", $vstring;

# Yup
print "@parts\n";

# A final shortcut, uses a fairly improbable ( but I guess still
# possible ) version to test whether the vstring is stored as
# UTF-8 ( looks like the answer is yes ).
$vstring2 = pack "U*", split /[.]/, qw$Revision: 2573.1111$[1];

printf "Decimal: %vd\n", $vstring2;