Sunday, March 15, 2015

My Bad Communication Skills

A couple weeks ago I asked how you "join the conversation" but based on feedback I got, I don't think I communicated well. I think people thought I meant "which blogs do you read?" What I really meant was: when you write a blog entry, where do you post the link so that it's seen by people who are interested in that subject?

So for example, when I write about Perl, I post to I want to blog about other topics too, like web development (JavaScript, CSS, etc); lifehacks; Unix, Linux, shell scripting; general tech / tech business; and database stuff. But when I blog I'd like it to have a chance of being seen. Please let me know your thoughts!

Saturday, February 21, 2015

How do you join the conversation? is great in that it's a stream of blog posts around a specific technology. Since I, like many of you, blog about other technologies too, I'd like to learn from you about other conversation streams. For me personally, the list of topics include:

  • Web development (JavaScript, CSS, etc)
  • Lifehacks
  • Unix, Linux, shell scripting
  • General tech / tech business
  • Database

I'll add what little knowledge I have on the topic:

There's reddit with corresponding subreddits on Unix and Perl. It looks like it's pretty routine to post blog entries on the Perl one at least, I'm not sure about the climate of other tech subreddits.

There are also subreddits for LifeProTips and Life Hacks. I've not yet participated in either, so again I'm not sure what the expectations are.

The Unix and Linux Forums, while not a "stream" of conversation, seems to be receptive to sharing ideas, and the people there are friendly and helpful.

And of course, Twitter with and without #perl and #unix hashtags. I say with or without as it seems like more popular bloggers, at least, don't bother with the hashtags. I'll also say that with or without the hashtags I haven't seen a lot of traffic coming from Twitter.

I'd appreciate anyone's advice, experience, or knowledge on this topic.


Tuesday, February 10, 2015

Fix Those Legacy Subroutines or Methods

Maybe you know the feeling… you go to add an option to that method or subroutine and… cue Jaws theme

sub update_shopping_cart {
    my $cart_id        = shift;
    my $item           = shift;
    my $quantity       = shift;

Argh. You don’t want your legacy code to break but you also don’t want to add a fourth unnamed parameter to the existing problem. And the solution is simple:

sub update_shopping_cart {
    my $cart_id        = shift;
    my $item           = shift;
    my $quantity       = shift;
    my $apply_discount = 0;        # Initialize the fourth parameter

    my $param1 = $cart_id;
    if ( ref $param1 eq 'HASH' ) {
        $cart_id        = $param1->{cart_id};
        $item           = $param1->{item};
        $quantity       = $param1->{quantity};
        $apply_discount = $param1->{apply_discount};

Now either of these work. The legacy call:

update_shopping_cart( 314, 'apples', 3 );

…or the new style:

    cart_id        => 314,
    item           => 'apples',
    quantity       => 3,
    apply_discount => 1,

Bonus: there is no way to use the new option with the old-style call. If someone wants to use it, they’ll need to switch to the new style.

  • The new call is self-documenting. In the original form of the call, you see “314” in the code by itself, and it’s not immediately obvious what it is. Now it’s nicely labeled.
  • Now that you have added the new format, you can painlessly add additional named parameters as needed.

  • It may be confusing to see two different styles of calls in your codebase. But, now you can transition the old code piecemeal.

Saturday, January 31, 2015

Command Line Project Manager (clpm) v1.0.1 released

clpm is designed to make managing sets of files easier at the Unix command line. It's free and open source. Please view the demo here. Find more info at

Sunday, January 18, 2015

Call for help with open source project "CLPM"

CLPM is my “Command Line Project Manager”. It’s a tool I wrote and have been using myself for several years now, and I am releasing it in the hope that others might find it useful.

Also, if you have been looking for an open source project to contribute to, here’s your chance! I don’t care what your level of experience is, if you think you have a useful comment or contribution, I’d like to hear from you!

There is a Todo section in the README, but I want to add a couple notes here:
  1. It’s currently not packaged, nor does it have an installer. This probably makes it much less likely to be adopted.
  2. I’m not sure how to promote it to make sure its audience (developers/sysadmins maybe) at least get a chance to see it, even if it ends up that it’s useful to nobody but me.
The project page has more details:

Thursday, January 08, 2015

CPAN Pull Request Challenge: The Pull Request

In my last report, I had received an ok from the module’s author to proceed with a pull request. The first thing I did, as I had with the modules referenced by Devel::StackTrace::WithLexicals, is to write an example for myself so I could see how it worked. Working from the synopsis, I had a difficult time writing a working piece of code. It occurred to me that this was the very place I could start with a Pull Request.

Since the module’s functionality combines that of two other modules (Devel::StackTrace and PadWalker), I wrote a working example showing both sets of functionality: specifically, the ability to walk back through the stack and the ability to read and modify a previous frame’s lexical variables.

Since I had not yet specified my area of focus to the author, I send him another email including the synopsis I had written and asked him for his thoughts on my changes. He liked them but asked that I replace my foos and bars with more realistic names. I had thought that foo and bar kept out of the way so that only the module’s functionality was on display, but he’s right: although the fake variable names do stay out of the way, they provide zero context for the user to become oriented while going through the code. I decided to use a problem domain that should be familiar to many developers: the shopping cart. Here’s the synopsis I ended up with:

use Devel::StackTrace::WithLexicals;
sub process_user {
    my $item_count = 20;
    print "$item_count\n";    # prints 21
sub price_items {
    my $trace = Devel::StackTrace::WithLexicals->new(
        unsafe_ref_capture => 1    # warning: can cause memory leak
    while ( my $frame = $trace->next_frame() ) {
        my $item_count_ref = $frame->lexical('$item_count');
        ${$item_count_ref}++ if ref $item_count_ref eq 'SCALAR';

I followed this excellent step-by-step guide on submitting a Pull Request and just a little while later it was approved!

Afterward I found this well-written post about having a good synopsis. What I had written conformed pretty well with the suggestions.

I had never done a pull request before this. There have been a couple times I contacted authors in the past to point out a bug or add a function, but most of the time I have not been an active participant.


  1. I am often busy with my own projects. Lately, I have tried to get more involved in the community. Much of this inspiration has come from the company I work for now, OmniTI, whose philosophy is very pro-open-source, speaking, contributing, etc. (side note - we’re hiring!)

  2. I can still be painfully shy. It sounds childish to put it in those terms, but it’s also accurate. It is difficult for me to “put myself out there” sometimes even if just in the form of an email.

  3. I had no idea where to start. This sounds like a cop-out, and in some ways it is, but I can honestly say I’ve spent hours looking around at different open source projects and not really found any place it looked like I could help.

But my shortcomings illustrate some of the things that make the CPAN Pull Request Challenge such a great project.

  1. It’s got a time-sensitive feel to it. It has dates attached to it, so feels like something you need to focus on now.

  2. It gave me an authority to point to when reaching out. Author: I’m contacting you not because I personally felt there was anything wrong with your module, but rather because this challenge told me to. So don’t be mad at me! :)

  3. It gave me a starting point. Being assigned a module is much more focused than having someone just say “Hey - contribute to something!” Now I could still have been bogged down in “what exactly do I contribute to in this module” but the challenge comes with tons of ideas on things to look at as well. Failing that, there’s always “Kwalitee”.

So, thank you, Neil Bowers - both for being a positive influence on the Perl and open source communities, and for helping me get out of my shell a bit.

Friday, January 02, 2015

My First Day on the CPAN Pull Request Challenge

So yesterday, I started on the CPAN Pull Request Challenge. I was assigned the module Devel::StackTrace::WithLexicals, so, I read the doc and installed it.

The doc references two other modules’ influence: Devel::StackTrace and PadWalker

So I figured I’d have a look at those first. Combining two examples from the doc for Devel::StackTrace, I wrote this:


use strict;
use warnings;

use Devel::StackTrace;

sub foo {

sub bar {
    my $trace = Devel::StackTrace->new();
    print $trace->as_string(); # like carp


Which gave me this:

$ ./
Trace begun at line 13
main::bar('bing', 1234) called at line 9
main::foo('bing') called at line 17


Next I looked at the doc for PadWalker. Based on the example provided, I wrote:


use strict;
use warnings;

use PadWalker qw(peek_my);

sub foo {
    my $abc = 123;


    print "magic! $abc\n";

sub bar {
    my $h = peek_my(1);


Which yields:

$ ./
magic! 124

So bar() increments foo()’s lexical variable $abc. What kind of witchcraft is this?!?

These are both very interesting modules. Changing lexicals from another scope defeats the purpose of a lexical, but as the doc points out, it can be useful for debugging purposes.

I reviewed the documentation for Devel::StackTrace::WithLexicals and the code, both of which can be viewed online at meta::cpan. In the left column are the links “Source (raw)” and “Browse (raw)” which are both handy to use when viewing the source.

Nothing immediately jumped out at me after reviewing the pull request ideas so I decided to contact the author to see if he had anything specific he’d like to see done. The author’s contact info is usually provided in the Author section of the documentation.

This is the email I sent:


I have volunteered in the CPAN Pull Request Challenge
and have been assigned your module Devel::StackTrace::WithLexicals to
contribute to if possible.

Ideas include, but aren't limited to:

I'd like to know if you are receptive to contributions to this module and if
you had any particular needs or wishes.  I am willing to contribute with any
aspect (features, bugs, testing, documentation, etc.)  If you are ok with
contributions (pending your approval of course) but you don't have anything
specific in mind, I will review the PR Ideas list myself and see if I can find
a way to contribute.

Thank you,
David M. Bradford

This morning I received a positive response from the author. Time to get to work!