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generate model using user:references vs user_id:integer
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how does rails know that user_id is a foreign key referencing user?
Rails itself does not know that user_id is a foreign key referencing user. In the first command rails generate model Micropost user_id:integer it only adds a column user_i...
Vim: Delete buffer without losing the split window
...ch is so simple, not requiring and entire script to run it. In my VIMRC, I now have this mapped for CTRL+C: nnoremap <C-c> :bp\|bd #<CR>
– Cloud
Jul 12 '13 at 17:40
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Why does the 260 character path length limit exist in Windows?
...used here for visual clarity and cannot be part of a valid path string.)
Now we see that it is 1+2+256+1 or [drive][:\][path][null] = 260. One could assume that 256 is a reasonable fixed string length from the DOS days. And going back to the DOS APIs we realize that the system tracked the current ...
Generating v5 UUID. What is name and namespace?
...ducible UUID for each namespace using "uuid -v5 $ROOTUUID $NAMESPACENAME". Now you can create unique UUIDs for keys within a namespace using "uuid -v5 $NAMESPACEUUID $KEY". These UUIDs can be thrown into a single key-value store with high probability of avoiding collision. This process can be repea...
Is returning by rvalue reference more efficient?
...e following
Beta_ab
Beta::toAB() const {
return Beta_ab(1, 1);
}
Now, it's properly moving a temporary Beta_ab object into the return value of the function. If the compiler can, it will avoid the move altogether, by using RVO (return value optimization). Now, you can do the following
Beta...
Optimistic vs. Pessimistic locking
I understand the differences between optimistic and pessimistic locking. Now could someone explain to me when I would use either one in general?
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What does “1 line adds whitespace errors” mean when applying a patch?
...free to ignore the warning or turn it off with git config apply.whitespace nowarn.
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Apply multiple functions to multiple groupby columns
... 0.687672 1.754877 0.672401
Using apply and returning a Series
Now, if you had multiple columns that needed to interact together then you cannot use agg, which implicitly passes a Series to the aggregating function. When using apply the entire group as a DataFrame gets passed into the fu...
How to use sed to remove the last n lines of a file
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I don't know about sed, but it can be done with head:
head -n -2 myfile.txt
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How to uncheck a radio button?
... explanation on the difference between attr() and prop() and why prop() is now preferable.
prop() was introduced with jQuery 1.6 in May 2011.
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