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hash n' params

by ybiC (Prior)
on Apr 07, 2001 at 18:57 UTC ( #70715=perlquestion: print w/replies, xml ) Need Help??

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

Monks whose opinions I respect have suggested a couple things to improve the quality of my scripts:
  1. use hash values instead of buckets o' scalar vars
  2. simplify subroutines by passing parameters properly

This ditty is a result of re-reading through merlyn's Llama and danger's EoPwP toward that end.   Have I got the right idea, or am I fullabeans?

P.S. Please ignore the fact that the following code is nothing more than a wrapper around 3 system calls.   Is mostly an exercise in learning a bit more Perl.   Using CPAN modules HTML::FormatPS and HTML::FormatText is on the Todos list {g}

#!/usr/bin/perl -w # # pod at tail use strict; use Cwd 'chdir'; my $dir = '~/'; my %exec = (); $exec{html2ps} = '/usr/bin/html2ps'; $exec{ps2pdf} = '/usr/bin/ps2pdf'; $exec{html2text} = '~/perl/html2text'; my %file = (); $file{rc} = '~/.html2psrc'; $file{html} = "$dir/original.html"; $file{tmp} = 'generated.tmp'; $file{ps} = ''; $file{pdf} = 'generated.pdf'; $file{txt} = 'generated.txt'; my @exists = @file{'rc', 'html'}; my @unlink = @file{'tmp', 'ps', 'pdf', 'txt'}; my @outfiles = @file{'ps', 'pdf', 'txt'}; print ("\nStarting $0 run.\n\n"); chdir "$dir" or die "Error chdir to $dir: $!"; foreach my $exec (values(%exec)) { &FILECHECK($exec, 'die'); } &FILECHECK($file{html}, 'die'); &FILECHECK($file{rc}, 'warn'); print "Ready to unlink prior ps, pdf, and txt files.\n"; print "<enter> to continue, ctrl+c to abort."; <STDIN>; foreach my $unlink(@unlink) { if (-e $unlink && -w _) { unlink $unlink or die "Error unlinking $unlink: $!"; } } system ("$exec{html2ps} -F $file{html} > $file{ps}") and die "Error running $exec{html2ps}: $!"; system ("$exec{ps2pdf} $file{ps} $file{pdf}") and die "Error running $exec{ps2pdf}: $!"; system ("$exec{html2text} < $file{html} > $file{tmp}") and die "Error running $exec{html2text}: $!"; open (TMP, "< $file{tmp}") or die "Error opening $file{tmp} RO: $!"; open (TEXT, "> $file{txt}") or die "Error opening $file{txt} WO: $!"; while (<TMP>) { s/&nbsp;/ /g; s/ / /g; print TEXT; } close TMP or die "Error closing $file{tmp}: $!"; close TEXT or die "Error closing $file{txt}: $!"; unlink $file{tmp} or die "Error unlinking $file{tmp}: $!"; print "\nCompleted $0 run.\n"; print " Original HTML file at:\n"; print " $file{html}\n"; print " Generated files at:\n"; foreach my $outfile (@outfiles) { print " $dir/$outfile\n"; } print ("\n"); ############################################### sub FILECHECK { my $file = $_[0]; my $ooot = $_[1]; unless (-e $file) { if ($ooot eq 'die') { die "\nError: $file not found where specified.\n\n"; } elsif ($ooot eq 'warn') { warn "\nCaution: $file not found where specified.\n"; } } } ############################################### =head1 Name =head1 Description Generates PostScript+PDF+text files from existing HTML. Insert <!--NewPage--> as needed in original.html then run this script +. html2ps does not handle frames, tables, or images in original HTML. =head1 Changelog 2001-04-07 07:20 Hashified variables Sub'd+parameterized filecheck 2001-04-05 Initial working Perl code 2001-04-03 Simple Bash script =head1 Todos Replace system call to html2ps with "use HTML::FormatPS". Replace system call to html2text with "use HTML::FormatText". (HTML::Tree and Font::AFM needed for above) Find perlish replacement for system call to ps2pdf. =head1 Author ybiC =head1 Required html2ps 1.0b1-8 gs-aladdin 5.50-8 ps2pdf html2text =head1 Tested On Debian 2.2, WinNT4, and Win2kPro Mozilla M18, 0.8 Netscape 4.75 Opera 5.02 IE 5.5 w3m 0.1.9-5 Lynx 2.8.3-1 gv 3.5.8-17 gsview32 2.6 Acrobat Reader 4.056 =head1 html2ps runcontrol /* ~/.html2psrc */ @html2ps { package { ImageMagick: 1; PerlMagick: 1; TeX: 1; Ghostscript: 1; check: weblint; libwww-perl: 1; path: "/usr/X11R6/bin:/usr/bin"; } paper { type: letter; } hyphenation { en { file: "/usr/share/texmf/tex/generic/hyphen/ushyph1.tex"; } } margin { top: 1; right: 2.5; bottom: 1.5; left: 2.5; } footer { alternate: 0; left: \$D; right: "page $N"; } } /* Standard style sheet definitions */ BODY { font-family: Helvetica; font-size: 11pt; } P { text-align: justify; } H1 { font-size: 19pt; text-align: center; font-weight: bold; } H2 { font-size: 14pt } H3 { font-size: 13pt } H4 { font-size: 12pt } H5 { font-size: 11pt; text-align: center; } H6 { font-size: 11pt; text-align: center; } =cut

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Re: hash n' params
by araqnid (Beadle) on Apr 07, 2001 at 20:38 UTC
    When you're initialising a hash that contains a group of settings, you can put them together like this:
    my %exec = ( html2ps => '/usr/bin/html2ps', ps2pdf => '/usr/bin/ps2pdf', html2text => '~/perl/html2text' );
    which IMHO looks nicer. You're explicitly allowed to use barewords on the left hand side of a =>, even if "use strict" is in force.
      Warning. A bug I recently learned about:
      use strict; my %trial_hash = ( foo => "bar", );
      does not run properly in a Perl program, but does if you use eval. So while I use the "big arrow", you should put it on the same line as the key, not the value.
Re: hash n' params
by stephen (Priest) on Apr 07, 2001 at 21:35 UTC
    A couple of comments:
    • Your <TYPE>my $dir</TYPE> at the top doesn't change during the lifetime of the script-- and it would be confusing if it did! Personally, I'd
      use constant DIR => '~/';
      or some such.
    • If you get an error in your system() calls, your error messages will be misleading. System() doesn't set $! on error. To get the return code on a system process that didn't return properly, use '$?'. I'd pull your system calls out into something like this:
      sub run_system { my (@params) = @_; system(@params) == 0 or die "System command @{[join ' ', @params]} failed: returned + @{[ $? >> 8 ]}; stopped"; }
    • You could replace the third function call with a call to open() (or open2()) to make it a bit more Perlish. It would require significantly more code, but would eliminate a temporary file.

    But, these are merely suggestions. It looks like good Perl to me.


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