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Run a callback only if an attribute has changed in Rails
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200
Rails 5.1+
class Page < ActiveRecord::Base
before_save :do_something, if: :will_save_chan...
When should I use @classmethod and when def method(self)?
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70
Your guess is correct - you understand how classmethods work.
The why is that these methods can...
Python: One Try Multiple Except
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edited Feb 23 '18 at 1:00
answered May 23 '11 at 10:13
v...
OrderBy descending in Lambda expression?
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edited Jul 19 '11 at 19:01
answered Oct 28 '09 at 6:34
Jo...
MySQL - length() vs char_length()
...> 3, 1
As you can see the Euro sign occupies 3 bytes (it's encoded as 0xE282AC in UTF-8) even though it's only one character.
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Is there a rule-of-thumb for how to divide a dataset into training and validation sets?
...for how to best divide data into training and validation sets? Is an even 50/50 split advisable? Or are there clear advantages of having more training data relative to validation data (or vice versa)? Or is this choice pretty much application dependent?
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Unresolved external symbol on static class members
...ou can just use the inline specifier (see https://stackoverflow.com/a/11711082/55721)
If using older versions of the C++ standard, you must add the definitions to match your declarations of X and Y
unsigned char test::X;
unsigned char test::Y;
somewhere. You might want to also initialize a static...
lock(new object()) — Cargo cult or some crazy “language special case”?
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edited Aug 20 '12 at 13:43
sehe
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git add all except ignoring files in .gitignore file
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edited Jul 7 '11 at 15:04
answered Jul 7 '11 at 14:59
Ni...
Difference between git pull --rebase and git pull --ff-only
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edited Aug 21 '14 at 16:04
answered Aug 21 '14 at 15:57
G...