On 15-Dec-01, Joel Neely wrote:
>> Perhaps Joel would now like to write a version in Perl that's
>> designed to be as clear as possible as apposed to as short as
>> possible?
>>
> To the everyday Perl hacker, what I published actually is both!
> No, really! ;-) The only things I could do to obviousify the
> script would be to write an explicit read/print loop (that's
> what the -p switch does) and embed comments in the RE that
> is the match pattern for the substitution. That would give us
> something like the following:
> 8<----------
> #!/usr/bin/perl -w
> while (<>) { # loop over all input (all file arguments)
> s/ # substitute in current line for this pattern...
> \b # boundary (e.g. whitespace or beginning of line)
> ( # begin subpattern
> \d{3} # exactly three digits
> - # followed by a hyphen
> )? # end subpattern and make it optional
> \d{3} # exactly three digits
> - # followed by a hyphen,
> \d{4} # exactly four more digits, and
> \b # a boundary (whitespace or end of line)
> /####/gx; # ... four octothorps wherever possible
> print; # print current line after substitution(s)
> }
> 8<----------
> but the addition of all the comments is hardly an improvement to
> a Perl programmer. That would be like showing someone who knows
> elementary algebra a paragraph of text that describes the quadratic
> formula, instead of simply writing (pardon the ASCII art...)
> ____________
> + / 2
> -b - / b - 4 a c
> V
> -------------------
> 2 a
> The notation really is intended to be minimalist; the price of
> using it is taking a little time to learn something new, as is
> the case with all programming languages. I suspect the person
> that has never seen REBOL before would find the comparable
> PARSE rule less than obvious as well.
Fair enough, though there is a "read", a "parse" and a "change" in my
REBOL example which does give some indication of what's being done
with the file-name, while the file-name is the only thing any
outsider would recognise in your Perl example.
> Of course, I could define variables to hold the parts of the RE
> and give them mnemonic names ...
> 8<----------
> #!/usr/bin/perl -w
> my $areacode = '(\d{3}-)?'; # 3 digits and hyphen, optional
> my $exchange = '\d{3}-'; # 3 digits and hyphen
> my $localine = '\d{4}'; # 4 digits
> my $phonenbr = "$areacode$exchange$localine";
> while (<>) { # loop over all input
> s/\b$phonenbr\b/####/gx; # hiding phone numbers in each line
> print; # and print the line
> }
> 8<----------
> ... but anyone who knows Perl will see that I had to do something
> subtle to make that work.
> Perhaps that would be more readable to some? What would one do
> in REBOL to make the PARSE rules more obvious to someone who
> doesn't speak REBOL as a native?
> -jn-
--
Carl Read
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