Как я реализовал GTD с помощью Remember The Milk

Если вы не знаете, что означает методология Getting Things Done — пожалуйста, почитайте о ней, прежде чем продолжать чтение этой статьи.

Однажды ко мне в гости зашел приятель и спросил, чем я обычно занимаюсь по работе. Я просто открыл Remember The Milk и показал ему список выполненных задач.

Remember The Milk — это очень гибкое и удобное веб-приложение для работы со списками задач, не навязывающее каких-то жестких правил работы. Благодаря этому RTM можно использовать просто как линейный список задач(вроде списка покупок в магазине), но можно реализовать на его основе свою мощную GTD-систему. Причем, реализации у разных людей получаются иногда совершенно непохожими.

RTM существует уже 4 или 5 лет, и я пользуюсь им почти с самого старта проекта. За это время я перепробовал десятки разных GTD-планировщиков, но всякий раз возвращался назад к RTM — ни одно другое средство не было для меня столь же удобным.

I asked on the vim mailing list how to see the name of Perl's current sub/method in the status line and Alan Young, the author of PPIx::IndexLines has a great suggestion which unfortunately relied on PPI. I'm working with very large modules and PPI ground to a halt for me. As a result, I took his suggestion and worked out the following.

First, make sure that your .vimrc has set laststatus=2 in it. That will ensure that you always get a status line, even if you only have one window (i.e., don't have split windows). Then drop the following into your .vim/ftplugin/perl.vim:

An introduction to eventmachine, and how to avoid callback spaghetti

http://rubylearning.com/blog/2010/10/01/an-introduction-to-eventmachine-and-how-to-avoid-callback-spaghetti/

This guest post is contributed by Martyn Loughran, who works at New Bamboo in London where he builds some very cool apps like Pusher. Pusher is a web service which finally makes web push easy using the brand new WebSocket protocol. When he’s not hacking away at the next great thing, he’s most likely to be found behind a cello; hacking in this context is less desirable. Alternatively find him on twitter as @mloughran where he tweets, reluctantly.

Evented programming has become cool lately, largely due to the very elegant node.js project. However, we’ve been evented in the Ruby world for many years thanks to eventmachine, which adds evented IO to Ruby. Writing evented code is often viewed as ‘hard’ or ‘back to front’, but it can actually be very elegant. You just need a few tricks up your sleeve.

One of the big challenges is understanding how to create clean abstractions. Since the structure of the code is so different to what you’re probably used to, you can quickly find yourself tied up in callback spaghetti. In this blog post I will explain some common patterns you can use while we combine the Twitter streaming API, Google’s language API, and a WebSocket server. No spaghetti is required, promise!

After getting started with eventmachine, we’ll discuss two common abstractions. Firstly deferrable objects which are like method calls which return asynchrnously. Secondly, how to abstract code that can trigger multiple events. Finally, we’ll add a WebSocket server into the same process to show off doing IO concurrently.

Предистория

Программируя мы часто сталкиваемся с необходимостью ограничить множество допустимых значений для некоторого типа данных. Так, например, день недели может иметь 7 разных значений, месяц в году - 12, а время года - 4. Для решения подобных задач во многих языках программирования со статической типизацией предусмотрен специальный тип данных - перечисление (enum). В Java перечисление появилось не сразу. Специализированная языковая конструкция enum была введена начиная с версии 1.5. До этого момента программисты использовали другие методы для реализации перечислений.

Конструкция enum

Начнем с примера. Давайте опишем с помощью enum тип данных для хранения времени года:

enum Season { WINTER, SPRING, SUMMER, AUTUMN }

Ну и простой пример его использования:

Season season = Season.SPRING;
if (season == Season.SPRING) season = Season.SUMMER;
System.out.println(season);

В результате выполнения которого на консоль будет выведено SUMMER. Думаю, что пример очевиден и в пояснениях не нуждается.

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%hash = map { $_ => 1 } @array;

It's not as short as the "@hash{@array} = ..." solutions, but those ones require the hash and array to already be defined somewhere else, whereas this one can take an anonymous array and return an anonymous hash.

What this does is take each element in the array and pair it up with a "1". When this list of (key, 1, key, 1, key 1) pairs get assigned to a hash, the odd-numbered ones become the hash's keys, and the even-numbered ones become the respective values.

 @hash{@array} = (1) x @array;

It's a hash slice, a list of values from the hash, so it gets the list-y @ in front.

From the docs:

If you're confused about why you use an '@' there on a hash slice instead of a '%', think of it like this. The type of bracket (square or curly) governs whether it's an array or a hash being looked at. On the other hand, the leading symbol ('$' or '@') on the array or hash indicates whether you are getting back a singular value (a scalar) or a plural one (a list).

@hash{@keys} = undef;

The syntax here where you are referring to the hash with an @ is a hash slice. We're basically saying $hash{$keys[0]} AND $hash{$keys[1]} AND $hash{$keys[2]} ... is a list on the left hand side of the =, an lvalue, and we're assigning to that list, which actually goes into the hash and sets the values for all the named keys. In this case, I only specified one value, so that value goes into $hash{$keys[0]}, and the other hash entries all auto-vivify (come to life) with undefined values. [My original suggestion here was set the expression = 1, which would've set that one key to 1 and the others to undef. I changed it for consistency, but as we'll see below, the exact values do not matter.]

When you realize that the lvalue, the expression on the left hand side of the =, is a list built out of the hash, then it'll start to make some sense why we're using that @. [Except I think this will change in Perl 6.]

The idea here is that you are using the hash as a set. What matters is not the value I am assigning; it's just the existence of the keys. So what you want to do is not something like: if ($hash{$key} == 1) # then key is in the hash instead: if (exists $hash{$key}) # then key is in the set

It's actually more efficient to just run an exists check than to bother with the value in the hash, although to me the important thing here is just the concept that you are representing a set just with the keys of the hash. Also, somebody pointed out that by using undef as the value here, we will consume less storage space than we would assigning a value. (And also generate less confusion, as the value does not matter, and my solution would assign a value only to the first element in the hash and leave the others undef, and some other solutions are turning cartwheels to build an array of values to go into the hash; completely wasted effort).

Модульные и функциональные тесты

Здесь я рассмотрю основные средства, используемые для модульного и функционального тестирования в Rails-приложениях. Напомню, что модульные тесты используются для тестирования логики приложения, которая расположена в моделях, а также для тестирования различных независимых участков приложения, например, хелперов (helpers).