Moments on Perl or other Programming Issues

Now I have a todo list command-line script. I want to have a to-do list for my wikipedia editing activities, a to-study list for math I want to study sparely, a to-study-or-to-code in computer programming and maybe a to-read list for books.

The current format of the todo list script is roughly like this:

C:\Users\user>todo.pl h

6. solve older Perl Weekly Challenges

And the codes of todo.pl is currently:
# For Strawberry Perl under Windows System
#
# todo.pl - Command-line Hacker's Todo List, v0.1, GNU gpl-3.0;
# I work with a file "hackerstodo.txt".
# Setup:
# 1. Put todo.pl within the folder
# having perl.exe, which is C:\Strawberry\perl\bin
# on Strawberry Perl Windows.
# 2. create a text file on a folder which does not require system admin authority, write your list of to-do stuff inside it
# 3. modify the value of the variable $hackstodo on line 21
#
# Author: FUNG Cheok Yin <cheokyin_restart@yahoo.com.hk> or
# <fungcheokyin@gmail.com>
#
# Mar 07, 2020
use strict;
use Switch;
use File::Copy;
use Cwd;

my $hackstodo = 'C:\D\hackerstodo.txt';  
# Do not set this file in a system folder
# or you will probably get "Access denied"

my $listofparameters = qq{
Command-line Hacker\'s Todo List
...
todo.pl h     \: display this help message that you are reading
};

my $originaldir = getcwd();
if (-e 'C:\Strawberry\perl\bin\hackerstodo~temp') {system 'del C:\Strawberry\perl\bin\hackerstodo~temp'};
if (-e $hackstodo) {
        copy($hackstodo, 'C:\Strawberry\perl\bin\hackerstodo~temp');
    system "del $hackstodo";
} else {
    system "echo > $hackstodo";
}
open LOG, 'C:\Strawberry\perl\bin\hackerstodo~temp';


my @list = ();

# get todo list from the text file $hackstodo
foreach (<LOG>) {
    {push @list, $_ unless $_ =~ /^\s*$/; }
}



# begin of subroutines

sub clear {
    copy $hackstodo ,'C:\Strawberry\perl\bin\todo-backup';
           @list = ();}

sub display {print "\n"; foreach (0..$#list) {print(($_+1), ". " , $list[$_], "\n") ; } }

sub suattop {my $top; $top = splice @list, $_[0]-1, 1; unshift @list, $top ;}

sub del {splice @list, $_[0]-1, 1;}

sub helpmsg {print $listofparameters;}

sub add {chomp($_ = <STDIN>); push @list, $_ unless $_ =~ /^\s*$/;}

sub bottom {my $temp = splice @list, $_[0]-1, 1; push @list, $temp;}

# end of subroutines


# handle the arguments
switch($ARGV[0]) {
    case "clear" {clear; print "The todo list is empty now."}
    case "t" {suattop($ARGV[1]); display}
    case "pop" {shift @list; print "Congratulations for finishing a task today!\n \n * * * * * * * * \nLatest TODO List \n"; display}
    case "a" { print "Enter new items:"; &add; print "\n"; &display}
    case "d" {del($ARGV[1]); display}
    case "b" {bottom($ARGV[1]); display}
    case "h" {helpmsg}
    else {display}
}

close LOG;

system 'del C:\Strawberry\perl\bin\hackerstodo~temp' if -e 'C:\Strawberry\perl\bin\hackerstodo~temp';
system "echo > $hackstodo";
open LOG2, ">$hackstodo" or die "wrong here, LOG2";

foreach (@list) {print LOG2 ($_, "\n");}
close LOG2;
chdir $originaldir;

Now, it seems that "object-oriented-ize"/"package-size" the script can satisfy my needs on what I said in the beginning of this post.

In Perl, there are several choices for OO. There is a built-in OO system; and there is Moose. I come across Moo also.

I am going to blog what I have learnt here. One-line background: I know some C++ but I don't know OO. The rest of March will be busy, but in April there are some public holidays; I expect I can update the progress in April. (Firstly, modify the indention! However, I find that the Rich Text Editor on Movable Type automagically converts the tabs. Then...)