YAPC::EU 2012 第三天

總算是比較涼爽一點了，前兩天的悶熱感，跟台灣的夏天沒兩樣。

這一天主要聽了 Perl6 相關的主題，像是新做的 p6doc 系統，可以直接用與程式中相同的 語法，查訊各內建的類別、方法、函式，算符：

• p6doc %% # 算符
• p6doc &any # 函式
• p6doc Any # 類別
• p6doc Str.flip # 類別方法

這真是十分的方便，比 perldoc 更加方便。目前 p6doc 程式已完成的同時，其文件內容也接繼補齊，並且可以成為許多 Perl6 實做的共用文件。已經有 Web 介面可以查： http://doc.perl6.org 。源碼在 github:perl6/doc

另一方面，由 Stevan Little 主導的 p5-MOP 實做也漸趨完整，與 Moose 十分神似，但 更加簡潔。

mst 的閉幕主講則再次回到「程式語言的興衰成敗」這個主題，曾經風華絕代的 Perl+CGI 組合，曾在 php + mod_php 改朝，又於 Ruby on Rails 換代。每個語言會輪流都有過熱潮， 但真正的價值，是在潮流過後留下來的東西，而不是在流行時所產生的那些垃圾產物。現在 還在說 Perl 程式碼難讀的人，多半只是沒有趕上時代，身在社群的各位一笑置之便行。或 著，展示一下用 Moose / Dancer 寫的程式，讓對方感受到當代 Perl 與 CGI 時代的巨大差 異。無可否認地，目前的 Perl 社群仍在穩定成長長，這便是這個語言與社群強建的證明。

這一天的其他筆記：

• YAPC EU 2012 Day 3
  • YAPC EU 2013 will be in Kiev
  • Stevan Little - perl5 mop.
    • Classes, Methods, Attributes, Intances
    • Sufficient MOP with: *{$pkg . '::foo'} = \&bar;
    • Class are first-class object, not just a string.
    • requires 5.14.2 for it's keyword-injection API.
    • single inheritance
      • resort to Roles if multiple-inheritance sort of thing is desired.
    • with rw accessors (lvalue accessors)
    • $self is magic inside a 'method' body block
    • positional parameter
    • 'has' keyword takes an variable name with sigils
      • has $balance ( is => 'ro' ) = 0;
    • 'role' keyword:
    • classes are no longer packages.
    • Exception classes, Fun, Try, etc etc...
  • doy. Dependency injection with Bread::Board
    • basically you'll always run into the timing that you wish one of your module can be replaced by another for, say, testing purpose.
    • Dependency Injection ~= "the inverse of garbage collection" (collection of garbages ? :)
    • Like Spoon::Hub, gather a collection of objects (aka "services") (not necessarrily singletons thoguh)
    • services can depends on other services
    • sort of like malloc, for named objects ?
  • duckduckgo
    • "Deep spice" -- zci (aka spice) based on the 1st page of search result. (good idea)
    • made money out of amazon affiliate program. cool.
    • duck duck goose
  • Patrick, perl6 doc
    • http://www.pmichaud.com/2012/pres/
    • p6doc -- written in perl6 and P6Pod
    • pretty new (2 month old), fresh blood requried
  • Maros command line app
    • MooseX::Getopt
    • MooseX::App
  • Perl6 regex
    • The operator: rx/.../
    • Apply: ~~ ~~,
    • m// and s/// are still there
    • match, comb, subst are Rx methods
    • New operators: ms// and ss/// : m:s // s:s///
    • /xms modifiers are default
    • /e modifiers are no more. just use {} in the replacement.
    • :P5 :Perl5 -- modifiers to make Rx perl5-compatible.
    • . still mach any char
    • \N not a newline
    • ^ begin of string . $ end of string
    • ^^ begin of line . $$ end of line
    • | longest match wins
    • || first match wins
    • [] non-capturing group
    • <[ ]> char classes
    • \s = \h | \v horizontal space, vertical space.
    • \d ** 5 quantifier (not \d{5}, {} always means code interpolation)
    • \d ** 2..5 (range object)
    • \d ** 2..* % ',' (% is "quantifier modifer") "matches 1,2,3,4"
    • $/ last matched
    • $/<...> $<...> named captures
    • $() all the positional captures
    • @() = $0,$1,$2,.. all the positional captures
  • mst ending keynote
    • we, as a group, are levelled up.
    • we have higher expectations
    • "Nice problem to have..."
    • Sustainable steady inexorable improvement.