Re: Generate list from a to arbitrary letter

[kennethk]

Auto increment and Auto decrement:

The auto-increment operator has a little extra builtin magic to it. If you increment a variable that is numeric, or that has ever been used in a numeric context, you get a normal increment. If, however, the variable has been used in only string contexts since it was set, and has a value that is not the empty string and matches the pattern /^[a-zA-Z]*[0-9]*\z/, the increment is done as a string, preserving each character within its range, with carry:
print ++($foo = "99");    # prints "100"
print ++($foo = "a0");    # prints "a1"
print ++($foo = "Az");    # prints "Ba"
print ++($foo = "zz");    # prints "aaa"

So, you could generate your list with:

my $max = 703;
my @letters;
my $current = 'a';
for (1 .. $max) {
    push @letters, $current++;
}

or some close variant.

[AnomalousMonk]

... a value that is not the empty string and matches the pattern  /^[a-zA-Z]*[0-9]*\z/ ...

This part of the documentation is confusing to me because the empty string matches the pattern:

>perl -wMstrict -le
"$_ = '';
 print 'match' if /^[a-zA-Z]*[0-9]*\z/;
"
match

I'm sure I've seen a discussion of this point, but I cannot lay my hands on it at the moment. Anyone...?

[Eily]

Well, there would be no point making two test if the result of one was the subset of the other (for exemple "a value that is positive and greater than 10"). In Perl, this condition would actually be: $matches if $_ ne '' and /^[a-zA-Z]*[0-9]*\z/ this was probably to have something easier to understand than one of those two patterns:

/^(?:
   [a-zA-Z]+ [0-9]*
   |
   [a-zA-Z]* [0-9]+
  )
\z/x;

/^(?=.)[a-zA-Z]*[0-9]*\z/;

The first one being a bit long, and the second not so beginner friendly.

[boftx]

I think this is a very easy-to-use approach. The only thing I would add would be a comment line reminding whoever has to maintain it down the road to read the docs for how the auto-increment operator works with string values if they are confused by what they see.