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Ruby on Rails - Import Data from a CSV file
...ase table. I do not want to save the CSV file, just take the data from it and put it into the existing table. I am using Ruby 1.9.2 and Rails 3.
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How to copy a row and insert in same table with a autoincrement field in MySQL?
In MySQL I am trying to copy a row with an autoincrement column ID=1 and insert the data into same table as a new row with column ID=2 .
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Re-raise exception with a different type and message, preserving existing information
I'm writing a module and want to have a unified exception hierarchy for the exceptions that it can raise (e.g. inheriting from a FooError abstract class for all the foo module's specific exceptions). This allows users of the module to catch those particular exceptions and handle them distinctly,...
How to implement classic sorting algorithms in modern C++?
The std::sort algorithm (and its cousins std::partial_sort and std::nth_element ) from the C++ Standard Library is in most implementations a complicated and hybrid amalgamation of more elementary sorting algorithms , such as selection sort, insertion sort, quick sort, merge sort, or heap sort....
How to duplicate object properties in another object?
...useful, I consider the idea of applying any rules to any situation harmful and unwise. Like all these pattern-driven development practices that are going on, so don't take it personal…
– Michael Krelin - hacker
Oct 3 '12 at 20:03
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Pairs from single list
...ed to process a list by pairs. I was wondering which would be the pythonic and efficient way to do it, and found this on Google:
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How to validate an email address in JavaScript
... for "RFC822" or "RFC2822" to get a proper regex.
– Randal Schwartz
Sep 8 '10 at 2:34
45
This doe...
How would you implement an LRU cache in Java?
...ructures would you use? I've already implemented one using LinkedHashMap and Collections#synchronizedMap , but I'm curious if any of the new concurrent collections would be better candidates.
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Can I make 'git diff' only the line numbers AND changed file names?
...rs", if you do not care about line numbers in the output see this question and answer.
10 Answers
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How should one use std::optional?
I'm reading the documentation of std::experimental::optional and I have a good idea about what it does, but I don't understand when I should use it or how I should use it. The site doesn't contain any examples as of yet which leaves it harder for me to grasp the true concept of this object. When...