标签: ruby

在Ruby中有没有办法将所有数组元素组合成一个字符串？

示例数组:

@arr = ['<p>Hello World</p>', '<p>This is a test</p>']

示例输出:

<p>Hello World</p><p>This is a test</p>

在哪里可以找到可在rails 3中使用的数据类型列表？(例如文本,字符串,整数,浮点数,日期等？)我会随机了解新的,但我希望有一个我可以轻松参考的列表.

我可以在一个文件中运行所有测试:

rake test TEST=path/to/test_file.rb

但是,如果我想在该文件中只运行一个测试,我该怎么做？

我正在寻找类似的功能:

rspec path/to/test_file.rb -l 25

很多时候人们使用符号作为Ruby哈希中的键.

使用字符串有什么好处？

例如:

hash[:name]

与

hash['name']

我使用rvm来安装ruby 1.9.3.即使它已成功安装,它也抱怨libyaml.现在,每当我想安装一个宝石(比如铁轨)时,这个警告会显示出来:

It seems your ruby installation is missing psych (for YAML output). To eliminate this warning, please install libyaml and reinstall your ruby.

我使用的是Mac OS X 10.7(Lion).

在不使用插件的情况下为Rails应用程序中的页面创建自定义标题的最佳方法是什么？

是否有类似于Python实用程序virtualenv的东西？

基本上它允许您将Python包安装到沙盒环境中,所以 easy_install django不会进入系统范围的site-packages目录,它将进入virtualenv创建的目录.

例如:

$ virtualenv test
New python executable in test/bin/python
Installing setuptools...cd .........done.
$ cd test/
$ source bin/activate
(test)$ easy_install tvnamer
Searching for tvnamer
Best match: tvnamer 0.5.1
Processing tvnamer-0.5.1-py2.5.egg
Adding tvnamer 0.5.1 to easy-install.pth file
Installing tvnamer script to /Users/dbr/test/bin

Using /Library/Python/2.5/site-packages/tvnamer-0.5.1-py2.5.egg
Processing dependencies for tvnamer
Finished processing dependencies for tvnamer
(test)$ which tvnamer 
/Users/dbr/test/bin/tvnamer

RubyGems有这样的东西吗？

SHA Hash函数

随着:limit查询,我会得到前N个记录.获得最后N条记录的最简单方法是什么？

我一直在尝试在Mac OS 10.9.3上安装Nokogiri,无论我尝试什么,安装最终都会失败,并显示以下错误消息:

$ sudo gem install nokogiri -- --with-xml2-include=/usr/local/Cellar/libxml2/2.9.1/include/libxml2 --with-xml2-lib=/usr/local/Cellar/libxml2/2.9.1/lib --with-xslt-dir=/usr/local/Cellar/libxslt/1.1.28 --with-iconv-include=/usr/local/Cellar/libiconv/1.14/include --with-iconv-lib=/usr/local/Cellar/libiconv/1.14/lib
Building native extensions with: '--with-xml2-include=/usr/local/Cellar/libxml2/2.9.1/include/libxml2 --with-xml2-lib=/usr/local/Cellar/libxml2/2.9.1/lib --with-xslt-dir=/usr/local/Cellar/libxslt/1.1.28 --with-iconv-include=/usr/local/Cellar/libiconv/1.14/include --with-iconv-lib=/usr/local/Cellar/libiconv/1.14/lib'
This could take a while...
Building nokogiri using packaged libraries.
ERROR:  Error installing nokogiri:
    ERROR: Failed to build gem native extension.

    /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb --with-xml2-include=/usr/local/Cellar/libxml2/2.9.1/include/libxml2 --with-xml2-lib=/usr/local/Cellar/libxml2/2.9.1/lib --with-xslt-dir=/usr/local/Cellar/libxslt/1.1.28 --with-iconv-include=/usr/local/Cellar/libiconv/1.14/include --with-iconv-lib=/usr/local/Cellar/libiconv/1.14/lib
Building nokogiri using packaged libraries.
checking for iconv.h... yes
checking for iconv_open() in iconv.h... no
checking for iconv_open() in -liconv... no
checking for libiconv_open() in iconv.h... no
checking for …