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Difference between “read commited” and “repeatable read”
...ame data again, it will find the previously read data in place, unchanged, and available to read.
The next isolation level, serializable, makes an even stronger guarantee: in addition to everything repeatable read guarantees, it also guarantees that no new data can be seen by a subsequent read.
Sa...
Image fingerprint to compare similarity of many images
...produce a normative mapping of the image data - store this with each image and then compare just the fingerprints. This is a complex algorithm and not for the faint of heart.
a few simple solutions are possible:
Create a luminosity histogram for the image as a fingerprint
Create scaled down versi...
What is the JSF resource library for and how should it be used?
The JSF <h:outputStylesheet> , <h:outputScript> and <h:graphicImage> components have a library attribute. What is this and how should this be used? There are a lot of examples on the web which use it as follows with the common content/file type css , js and img (or ima...
How to detect if a script is being sourced
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This seems to be portable between Bash and Korn:
[[ $_ != $0 ]] && echo "Script is being sourced" || echo "Script is a subshell"
A line similar to this or an assignment like pathname="$_" (with a later test and action) must be on the first line of the s...
Prefer composition over inheritance?
...this case, it makes sense to extract it out as an interface / class / both and make it a member of both classes.
Update: Just came back to my answer and it seems now that it is incomplete without a specific mention of Barbara Liskov's Liskov Substitution Principle as a test for 'Should I be inher...
What good are SQL Server schemas?
I'm no beginner to using SQL databases, and in particular SQL Server. However, I've been primarily a SQL 2000 guy and I've always been confused by schemas in 2005+. Yes, I know the basic definition of a schema, but what are they really used for in a typical SQL Server deployment?
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Unit testing code with a file system dependency
...at you clean up after youself -- delete any temporary files you created -- and that you don't accidentally overwrite an existing file that happened to have the same filename as a temporary file you were using. Always use relative paths and not absolute paths.
It would also be a good idea to chdir(...
OpenCV C++/Obj-C: Detecting a sheet of paper / Square Detection
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This is a recurring subject in Stackoverflow and since I was unable to find a relevant implementation I decided to accept the challenge.
I made some modifications to the squares demo present in OpenCV and the resulting C++ code below is able to detect a sheet of paper ...
Python class inherits object
...erit from object?
In Python 3, apart from compatibility between Python 2 and 3, no reason. In Python 2, many reasons.
Python 2.x story:
In Python 2.x (from 2.2 onwards) there's two styles of classes depending on the presence or absence of object as a base-class:
"classic" style classes: the...
What is the difference between IEnumerator and IEnumerable? [duplicate]
What are the differences between IEnumerator and IEnumerable?
4 Answers
4
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