大约有 40,000 项符合查询结果（耗时：0.0475秒） [XML]
Can someone explain collection_select to me in clear, simple terms?
...order(..) or something like that.
# In your example it is:
Author.all,
# then you should specify methods for generating options
:id, # this is name of method that will be called for every row, result will be set as key
:name_with_initial, # this is name of method that will be ...
正则表达式 30 分钟入门教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...代表的含意与\d就是完全一致的：一位数字；同理[a-z0-9A-Z_]也完全等同于\w（如果只考虑英文的话）。
下面是一个更复杂的表达式：\(?0\d{2}[) -]?\d{8}。
“(”和“)”也是元字符，后面的分组节里会提到，所以在这里需要使用转义...
Converting an array of objects to ActiveRecord::Relation
I have an array of objects, let's call it an Indicator . I want to run Indicator class methods (those of the def self.subjects variety, scopes, etc) on this array. The only way I know to run class methods on a group of objects is to have them be an ActiveRecord::Relation. So I end up resorting to...
Is pass-by-value a reasonable default in C++11?
...by value into functions and methods is slow for large objects, and is generally frowned upon. Instead, C++ programmers tend to pass references around, which is faster, but which introduces all sorts of complicated questions around ownership and especially around memory management (in the event that ...
Logging framework incompatibility
I'm building a small Java app and hoping to use logback for logging.
3 Answers
3
...
“Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” using PHP
... can be used to detect if a variable has been already initialized. Additionally and more ideal is the solution of empty() since it does not generate a warning or error message if the variable is not initialized.
From PHP documentation:
No warning is generated if the variable does not exist. T...
SASS - use variables across multiple files
I would like to keep one central .scss file that stores all SASS variable definitions for a project.
6 Answers
...
Grep only the first match and stop
...two the last time I looked. It seems like I have too many arguments, especially without getting the desired outcome. :-/
5...
Pushing a local branch up to GitHub
...
If you are really lazy, you can push all local branches by simply using
git push --all
--all
Push all branches (i.e. refs under refs/heads/); cannot be used with
other <refspec>.
...
Evaluating a mathematical expression in a string
...p://pyparsing.wikispaces.com/message/view/home/15549426
'''
__note__ = '''
All I've done is rewrap Paul McGuire's fourFn.py as a class, so I can use it
more easily in other places.
'''
class NumericStringParser(object):
'''
Most of this code comes from the fourFn.py pyparsing example
...