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Reference: What is variable scope, which variables are accessible from where and what are “undefined
...scope" in PHP? Are variables from one .php file accessible in another? Why do I sometimes get "undefined variable" errors?
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Rails 3 check if attribute changed
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Check out ActiveModel::Dirty (available on all models by default). The documentation is really good, but it lets you do things such as:
@user.street1_changed? # => true/false
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Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier
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I have had this error many times and it can be quite hard to track down...
Basically, what hibernate is saying is that you have two objects which have the same identifier (same primary key) but they are not the same object.
I would suggest you break down your code, i.e. comment out bits un...
String literals: Where do they go?
...nto the process space as read-only (which is why you can't change it).
It does vary by platform. For example, simpler chip architectures may not support read-only memory segments so the data segment will be writable.
Rather then try to figure out a trick to make string literals changeable (it wil...
How to use pip with Python 3.x alongside Python 2.x
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The approach you should take is to install pip for Python 3.2.
You do this in the following way:
$ curl -O https://bootstrap.pypa.io/get-pip.py
$ sudo python3.2 get-pip.py
Then, you can install things for Python 3.2 with pip-3.2, and install things for Python 2-7 with pip-2.7. The pip com...
Difference between java.lang.RuntimeException and java.lang.Exception
...rence between java.lang.RuntimeException and java.lang.Exception ? How do I decide which one to extend if I create my own exception?
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How do I access the host machine itself from the iPhone simulator
...ding on jaminguy's answer, MAC OSX also has a built in Apache server. Just do a quick google search.....
– Sid
May 20 '11 at 23:00
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What is the difference between the kernel space and the user space?
What is the difference between the kernel space and the user space? Do kernel space, kernel threads, kernel processes and kernel stack mean the same thing? Also, why do we need this differentiation?
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Why do I need to override the equals and hashCode methods in Java?
Recently I read through this
Developer Works Document .
29 Answers
29
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How do I copy an object in Java?
...y object has also a clone method which can be used to copy the object, but don't use it. It's way too easy to create a class and do improper clone method. If you are going to do that, read at least what Joshua Bloch has to say about it in Effective Java.
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