Domon's Programming Notes

Keynote - Brad Fitzpatrick | DjangoCon on blip.tv

Thu, 22 Sep 2011 05:10:00 -0700

via blip.tv

並非別人就是天才，自己就是笨蛋。
- 自己知道自己哪裡癢、怎麼癢，會癢就抓！

為什麼要自己來？
- 可以是為了學習，也可以是因為不想學習。自己來是有多難？

簡單 != 很快可以解決
花時間 != 困難

東西放出去，就要有心理準備持續收到 mail，即使那只是自己一時的小玩具。
- 技巧：減少自己的 address 曝光、提早建立社群

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The protocol-relative URL « Paul Irish

Fri, 05 Aug 2011 03:37:00 -0700

There's this little trick you can get away with that'll save you some headaches:
<img src="//domain.com/img/logo.png">
If the browser is viewing that current page in through HTTPS, then it'll request that asset with the HTTPS protocol, otherwise it'll typically* request it with HTTP. This prevents that awful "This Page Contains Both Secure and Non-Secure Items" error message in IE, keeping all your asset requests within the same protocol.

*Of course, if you're viewing the file locally, it'll try to request the file with the file:// protocol.

via paulirish.com

https 的頁面中若送出 http 的 request，就會收到 browser 的警告。

若該 resource 同時可以透過 https 和 http 取得，則不要把 protocol 寫出來，在 https 的頁面中 browser 會自行決定採 https。

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Documentation is freaking awesome // Speaker Deck

Wed, 29 Jun 2011 04:27:00 -0700

via speakerdeck.com

寫文件有很多好處，包含讓更多人了解你的 project，進而願意使用甚至 contribute；
寫文件也是個機會，讓自己停下來了解自己的 code 是否有問題。

slide 中提到不少產生 doc 的好工具，像是 RDoc、YARD、TomDoc……等。

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Quick Tip: Understanding CSS Specificity | Nettuts+

Fri, 14 May 2010 23:22:00 -0700

via net.tutsplus.com

CSS rule 的 specificity 越高，priority 越高。
specificity 可由該 rule 包含的 selector 計算總分
- HTML element: 1
- class: 10
- id: 100

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Why Ruby

Tue, 04 May 2010 07:16:00 -0700

via slideshare.net

1. 好的語言不該限制思考；
2. 簡潔 != 簡單。

作者在別場演講的講稿（應該是同份 slide）：
http://www.rubyist.net/~matz/slides/oscon2003/power.txt

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Ruby製アプリケーションを配布するn個の方法 (1/2) - 原悠‐ニコニコ動画(9)

Thu, 29 Apr 2010 09:42:00 -0700

【ニコニコ動画】Ruby製アプリケーションを配布するn個の方法 (1/2) - 原悠

via nicovideo.jp

1. RubyScript2Exe：把所有檔案在 temp dir 展開，速度比較慢。作者很久沒更新了，Ruby 1.8.6 之後無法使用。
2. Exerb：不使用 temp dir 的方式，有 RubyGems 相關問題，作者自己沒什麼在用了。
3. OCRA：只包進需要的檔案，所以比較快。建議使用。
4. Crate：把 code 和 lib 存在 sqlite3 db 裡。
5. Zip：把 win32 版 ruby 和所寫的程式放一起，寫個 .bat 檔啟動。Exerb 的作者現在用這方法。

個人經驗：
之前嘗試的時候，RubyScript2Exe 失敗；OCRA 在 XP 上可以，Win7 x64 不行；Exerb 想試還沒試（作者還有在更新）；Crate 好像值得一試；zip 真是最後的終極解法（但和沒解差不多）。

演講的下半段，是把 web app 包起來當做桌面程式。

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OSDC.tw - Building a platform from open source

Thu, 29 Apr 2010 02:06:57 -0700

via slideshare.net

- Ability to scale != performance
- Premature optimization is the root of all evil. e.g. " v.s. ', echo v.s. print
- Do not use .htaccess (move to real apache config)

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Assigning property values, Cascading, and Inheritance

Fri, 29 Jan 2010 07:23:15 -0800

/* From the user's style sheet */
p { text-indent: 1em ! important }
p { font-style: italic ! important }
p { font-size: 18pt }

/* From the author's style sheet */
p { text-indent: 1.5em !important }
p { font: normal 12pt sans-serif !important }
p { font-size: 24pt }

via w3.org

- 加上 ! important 的 declaration 會蓋過普通的 declaration 。
- 一般情況下，author 的 style 會蓋過 user 的 style；但加上 ! important 時，則是 user 蓋過 author。
- 例子中，前兩行 declaration 是 user 勝，第三行則是 author 勝。

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The GNU General Public License - GNU Project - Free Software Foundation (FSF)

Sun, 24 Jan 2010 17:55:00 -0800

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
Also add information on how to contact you by electronic and paper mail.

If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
<program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.

via gnu.org

細節可參考「How to use GNU licenses for your own software」。

- 隨軟體附上檔名 COPYING，內容是 GPL 的純文字版。

- 每個檔案開頭最好都要寫「This file is part of <program>.」，接著是 copyright notice（誰寫的）和 copying permission statement（表明使用 GPL）。把 <program> 和「this program」換成軟體名稱。

- 可以要求工作的雇主或學校簽署 copyright disclaimer，以免未來他們說著作權是屬於他們的。

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jLinq - LINQ for JSON

Sat, 23 Jan 2010 21:58:27 -0800

var results = jLinq.from(data.users)
    .is("admin")
    .greater("age", 25)
    .orderBy("-age") //the '-' means descending
    .select();

via hugoware.net

LINQ 是 .NET 的 lib，選取部分資料時，可以 method chaining 方式，達到類似 SQL 的 operator，如 select、where……等的效果。
jlinq 這個 lib 則讓使用者可以對 JSON 裡的 object 下 LINQ style query。

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Using Git to manage a web site

Sat, 23 Jan 2010 04:52:00 -0800

The remote repository

On the server, we create a new repository to mirror the local one.
$ mkdir website.git && cd website.git
$ git init --bare
Initialized empty Git repository in /home/ams/website.git/
Although this mirror starts out "bare" (i.e., with no work tree of its own), we add a detached work tree that corresponds to the web server's DocumentRoot (this directory must exist; Git will not create it for you.)
$ mkdir /var/www/www.example.org
$ git config core.worktree /var/www/www.example.org
$ git config core.bare false
$ git config receive.denycurrentbranch ignore
Then we define (and enable) a post-receive hook.
$ cat > hooks/post-receive
#!/bin/sh
git checkout -f
$ chmod +x hooks/post-receive
Back on the workstation, we define a name for the remote mirror, and then mirror to it, creating a new "master" branch there.
$ git remote add web ssh://server.example.org/home/ams/website.git
$ git push web +master:refs/heads/master
On the server, /var/www/www.example.org should now contain a copy of your files, independent of any .git metadata.

The update process

Nothing could be simpler. In the local repository, just run
$ git push web
This will transfer any new commits to the remote repository, where the post-receive hook will immediately update the DocumentRoot for you.

(This is more convenient than defining your workstation as a remote on the server, and running "git pull" by hand or from a cron job, and it doesn't require your workstation to be accessible by ssh.)

via toroid.org

概念：local repo <-> remote repo (bare repo + work tree)

平常工作在 local repo，推到 remote 的 bare repo，由 hook 自動更新到 work tree（亦即網站 code 的所在，和 bare repo 不同目錄）。

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Is there an "exists" function for jQuery - Stack Overflow

Fri, 22 Jan 2010 04:20:33 -0800

jQuery.fn.exists = function(){return jQuery(this).length>0;}
if ($(selector).exists()) {
// Do something
}

via stackoverflow.com

使用 jQuery 時，想知道 element 是否存在，可從 length 判斷。
若大於 0 則代表選到 1 個以上的 element。
把這個判斷的動作寫成 exists 函式，是個方便的作法。

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Do you say "Click the button" or "Click ON the button" ? - Stack Overflow

Sun, 20 Dec 2009 21:07:09 -0800

Although it's not fashionable to give props to Microsoft these days, the Microsoft Manual of Style For Technical Publications is a great reference for answering these sorts of questions.

If anything, it sets a familiar standard that can be applied throughout your documentation.

For this particular case, it recommends:

The words the and button should be omitted.

Do not use click on.

Dialog box options should be boldface.

So, do not write:

Click the Cancel button to close the window.

Instead, write:

Click Cancel.

Also, since users usually do not RTFM, and certainly will not RTFM to find out what the Cancel button does, they will appreciate fewer words getting in the way of the information they really need to find.

via stackoverflow.com

- "Click on" 的 "on" 絕對是多餘的，不要用。
- "the ... button" 其實也很多餘。
- 對一般使者為對象時，"to ..." 也可以不用寫。
- 結論：例如 "Click Cancel." 這樣寫就好，然後按鈕名稱 "Cancel" 要粗體。

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Ruby Programming/Syntax/Operators - Wikibooks, collection of open-content textbooks

Fri, 28 Aug 2009 06:58:56 -0700

Conditional assignment

x = find_something() #=>nil
 x ||= "default"      #=>"default" : value of x will be replaced with "default", but only if x is nil or false
 x ||= "other"        #=>"default" : value of x is not replaced if it already is other than nil or false

Operator ||= is a shorthand form of the expression:

x = x || "default"

Operator ||= can be shorthand for code like:

x = "(some fallback value)" if x.nil?

via en.wikibooks.org

x = ... if x.nil?

可以簡單寫成：

x ||= ...

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Joseph Smarr: "High-performance JavaScript: Why Everything You've Been on Yahoo! Video

Mon, 24 Aug 2009 09:13:00 -0700

via video.yahoo.com

- 網頁速度很重要。
- js 越多行，下載、執行時間越久。
- js lib 只用需要的部份。
- js 在需要的時候再 load，UI 用到時再 draw。
- js 放網頁最後，讓使用者先看到網頁。
- UI 一步步 load，看起來就不覺得慢。
- 使用者動作先處理，設 setTimeout(0) 晚點繼續。
- server 端在一定範圍內做 cache，如 address book 往上轉馬上讀到。
- 別做 DOM manipulation，用 innerHTML 和 array.join("")。
- 避免 dynamic CSS-class 和 CSS math。
- 避免 memory allocation，如 string-splitting。

p.s. 那影片是兩年前的東西，從這裡和這裡的實際測試看來，現在 DOM 比 innerHTML 快？

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Testing if an array is empty - PHP answers

Thu, 20 Aug 2009 02:26:00 -0700

if(array_filter($ary))
$ary contains at least one non-empty element
else
$ary contains 0 elements or all elements are empty

via bytes.com

empty() 能判斷不含任何 key 或 value 的空 array。

如果要做「不管有沒有 key，全部 value 都是空的」這樣的判斷，可以利用 array_filter( $input [, $callback] )。
$input 是要被 filter 的 array，$callback 是要把 value 送去處理的 function 名稱，array_filter() 會把 callback function 回傳 false 的 element 移除，傳回 filter 後的 array。

不設 callback function 時，它會把 array 的 value 轉換成 bool，空字串轉成 bool 後是 false。
所以，如果 array 所有的 value 都是空的，便會得到一個空 array，亦即範例中的 else 部份（if 亦是將變數轉為 bool 判斷）。

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Ruby 程式語言簡介

Thu, 06 Aug 2009 09:32:57 -0700

via slideshare.net

- 只有 false 和 nil 是假，其他為真（0 也是真、空字串也是真）。
- 方便的 iterators：map（修改各元素）、find_all、delete_if、sort!、inject（跑過各元素取得一統計值，如總和）等。
- 在 function 定義中使用 yield 敘述，傳 code block 給 function，該 code block 將在 yield 的位置執行。
- 可將 code block 設為一個 Proc 物件。
- module 裡可以放 method 和 constant，而 class 可以 include module（此動作稱為 mixin），解決多重繼承的問題。
- duck typing：不需 inheritance 即可達到 polymorphism。即使 class 內容不完全相，method 同名即可。
- meta programming（用程式寫程式）：define_method（動態定義 method）、method_missing（程式指定的 method 未定義時就執行它）
- rails clone：PHP on TRAX、CakePHP、TurboGears（Python）、Catalyst（Perl）、Grails（Groovy）等。
- Active Record：定義、存取 DB 等皆可由 object method 操作。

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Random Numbers in Ruby

Fri, 17 Jul 2009 20:50:00 -0700

Ruby comes with a pretty nice random number generator. The method to get a randomly chosen number is rand. If you call rand just like that, you'll get a float greater than or equal to 0.0 and less than 1.0. If you give rand an integer (5 for example), it will give you an integer greater than or equal to 0 and less than 5 (so five possible numbers, from 0 to 4).

Let's see rand in action.
puts rand
puts rand
puts rand
puts(rand(100))
puts(rand(100))
puts(rand(100))
puts(rand(1))
puts(rand(1))
puts(rand(1))
puts(rand(99999999999999999999999999999999999999999999999999999999999))
puts('The weatherman said there is a '+rand(101).to_s+'% chance of rain,')
puts('but you can never trust a weatherman.')
0.866769322351658
0.155609260113273
0.208355946789083
61
46
92
0
0
0
22982477508131860231954108773887523861600693989518495699862
The weatherman said there is a 47% chance of rain,
but you can never trust a weatherman.
Note that I used rand(101) to get back numbers from 0 to 100, and that rand(1) always gives back 0. Not understanding the range of possible return values is the biggest mistake I see people make with rand; even professional programmers; even in finished products you can buy at the store. I even had a CD player once which, if set on "Random Play," would play every song but the last one... (I wonder what would have happened if I had put in a CD with only one song on it?)

via pine.fm

如果 n 是 int，rand(n) 會跑出的亂數是 0 ~ (n-1)。
所以，想要 0 ~ 100，就要用 rand(101)。

C++ 如果用 rand() %100，也是產生 0 ~ 99；
php 則是 rand(min, max)，直接指定最大、最小值。

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Domon's Programming Notes

Keynote - Brad Fitzpatrick | DjangoCon on blip.tv

The protocol-relative URL « Paul Irish

Documentation is freaking awesome // Speaker Deck

Quick Tip: Understanding CSS Specificity | Nettuts+

Why Ruby

Ruby製アプリケーションを配布するn個の方法 (1/2) - 原 悠‐ニコニコ動画(9)

OSDC.tw - Building a platform from open source

Assigning property values, Cascading, and Inheritance

The GNU General Public License - GNU Project - Free Software Foundation (FSF)

jLinq - LINQ for JSON

Using Git to manage a web site

The remote repository

The update process

Is there an "exists" function for jQuery - Stack Overflow

Do you say "Click the button" or "Click ON the button" ? - Stack Overflow

Ruby Programming/Syntax/Operators - Wikibooks, collection of open-content textbooks

Joseph Smarr: "High-performance JavaScript: Why Everything You've Been on Yahoo! Video

Testing if an array is empty - PHP answers

Ruby 程式語言簡介

Random Numbers in Ruby

Ruby製アプリケーションを配布するn個の方法 (1/2) - 原悠‐ニコニコ動画(9)