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Hidden features of Perl?
What are some really useful but esoteric language features in Perl that you've actually been able to employ to do useful work?
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SQL UPDATE SET one column to be equal to a value in a related table referenced by a different column
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Without the update-and-join notation (not all DBMS support that), use:
UPDATE QuestionTrackings
SET QuestionID = (SELECT QuestionID
FROM AnswerTrackings
WHERE AnswerTrackings.AnswerID = QuestionTrackings.AnswerID)
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Is there an equivalent to CTRL+C in IPython Notebook in Firefox to break cells that are running?
...errupt the entire iPython Notebook server. This will stop iPython Notebook alltogether, which means it won't be possible to restart or save your work, so this is obviously not a great solution (you need to hit CTRL+C twice because it's a safety feature so that people don't do it by accident). In cas...
How can I read a text file in Android?
... If you wan to read this file from res/raw foldery, where the file will be indexed and is accessible by an id in the R file:
InputStream is = getResources().openRawResource(R.raw.test);
Good example of reading text file from res/raw folder
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Advantages to Using Private Static Methods
When creating a class that has internal private methods, usually to reduce code duplication, that don't require the use of any instance fields, are there performance or memory advantages to declaring the method as static?
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Symbolic links and synced folders in Vagrant
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Virtualbox does not allow symlinks on shared folders for security reasons. To enable symlinks the following line needs to be added to the vm provider config block in the Vagrantfile:
config.vm.provider "virtualbox" do |v|
v.customize ["sete...
How to refer to relative paths of resources when working with a code repository
...Try to use a filename relative to the current files path. Example for './my_file':
fn = os.path.join(os.path.dirname(__file__), 'my_file')
In Python 3.4+ you can also use pathlib:
fn = pathlib.Path(__file__).parent / 'my_file'
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How to check 'undefined' value in jQuery
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JQuery library was developed specifically to simplify and to unify certain JavaScript functionality.
However if you need to check a variable against undefined value, there is no need to invent any special method, since JavaScript has a typeof operator, which is...
Python “raise from” usage
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The difference is that when you use from, the __cause__ attribute is set and the message states that the exception was directly caused by. If you omit the from then no __cause__ is set, but the __context__ attribute may be set as well, and the traceback then shows the co...
Python's json module, converts int dictionary keys to strings
...which implement a __hash__ method. (The Lua docs suggest that it automatically uses the object's ID as a hash/key even for mutable objects and relies on string interning to ensure that equivalent strings map to the same objects).
In Perl, Javascript, awk and many other languages the keys for hash...