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Ruby on Rails Callback, what is difference between :before_save and :before_create?
...plain in detail what the :before_save and :before_create Ruby on Rails callbacks are, and what they have to do with Rails validations? Does validation occur after :before_save or :before_create ?
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How to get a reference to current module's attributes in Python
...his is the module
where it is defined, not the module
from which it is called).
http://docs.python.org/library/functions.html#globals
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When should I use jQuery deferred's “then” method and when should I use the “pipe” method?
...You'd use .pipe() to (pre)filter the result somehow. The return value of a callback to .pipe() will be passed as argument to the done and fail callbacks. It can also return another deferred object and the following callbacks will be registered on this deferred.
That is not the case with .then() (or ...
Assign a variable inside a Block to a variable outside a Block
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The block is called well after where it looks like it should be called, in other words, blocks don't run 'right away'.
– Tom Andersen
Dec 8 '14 at 20:46
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Why use HttpClient for Synchronous Connection
I am building a class library to interact with an API. I need to call the API and process the XML response. I can see the benefits of using HttpClient for Asynchronous connectivity, but what I am doing is purely synchronous, so I cannot see any significant benefit over using HttpWebRequest .
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Which “href” value should I use for JavaScript links, “#” or “javascript:void(0)”?
...developers inevitably leads to some using the return value of the function called like this:
function doSomething() {
//Some code
return false;
}
But then they forget to use return doSomething() in the onclick and just use doSomething().
A second reason for avoiding # is that the final r...
Is there a query language for JSON?
... formally specified, but also supported by many JSON libraries. So I would call it actual real useful standard, although due to its limited expressiveness it may or may not be considered Query Language per se.
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How can I create a copy of an object in Python?
...')
>>> tuple_copy_attempt = a_tuple.copy()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'copy'
Tuples don't even have a copy method, so let's try it with a slice:
>>> tuple_copy_attempt = a_tup...
What is the difference between . (dot) and $ (dollar sign)?
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The short and sweet version:
($) calls the function which is its left-hand argument on the value which is its right-hand argument.
(.) composes the function which is its left-hand argument on the function which is its right-hand argument.
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When should I use perror(“…”) and fprintf(stderr, “…”)?
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Calling perror will give you the interpreted value of errno, which is a thread-local error value written to by POSIX syscalls (i.e., every thread has it's own value for errno). For instance, if you made a call to open(), and...