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Spring @Transactional - isolation, propagation
Can someone explain what isolation & propagation parameters are for in the @Transactional annotation via real-world example?
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Can “this” ever be null in Java?
...sn't null.
The JLS says :
When used as a primary expression, the keyword this denotes a value that is a reference to the object for which the instance method was invoked (§15.12), or to the object being constructed.
If you invoked a method from an object, then the object exists or you would...
Bundler: Command not found
I am hosting on a vps, ubuntu 10.04, rails 3, ruby and mysql installed correctly by following some tutorials. If I run bundle check or bundle install I get the error '-bash: bundle: command not found'. From gem list --local I see 'bundler (1.0.2, 1.0.0)' is installed.
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How to work around the lack of transactions in MongoDB?
...telling me to switch back to regular RDBMS systems if I need transactions or use atomic operations or two-phase commit . The second solution seems the best choice. The third I don't wish to follow because it seems that many things could go wrong and I can't test it in every aspect. I'm having a ...
Has an event handler already been added?
...d it needs to be flagged, which the event handler took care of properly before. However now when the objects are deserialized it isn't getting the event handler.
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Convert two lists into a dictionary
...ctionary)
{'a': 1, 'b': 2, 'c': 3}
Voila :-) The pairwise dict constructor and zip function are awesomely useful: https://docs.python.org/3/library/functions.html#func-dict
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Can iterators be reset in Python?
Can I reset an iterator / generator in Python? I am using DictReader and would like to reset it to the beginning of the file.
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How to cat a file containing code?
...cument delimiter after <<.
cat <<'EOF' >> brightup.sh
or equivalently backslash-escape it:
cat <<\EOF >>brightup.sh
Without quoting, the here document will undergo variable substitution, backticks will be evaluated, etc, like you discovered.
If you need to expand...
Storing Python dictionaries
...iles, but there are obvious challenges to this. Are there simple ways to store a dictionary (or sets of dictionaries) in a JSON or pickle file?
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Run PHP Task Asynchronously
I work on a somewhat large web application, and the backend is mostly in PHP. There are several places in the code where I need to complete some task, but I don't want to make the user wait for the result. For example, when creating a new account, I need to send them a welcome email. But when they h...