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When to use EntityManager.find() vs EntityManager.getReference() with JPA
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I usually use getReference method when i do not need to access database state (I mean getter method). Just to change state (I mean setter method). As you should know, getReference returns a proxy object which uses a powerful featu...
AttributeError: 'module' object has no attribute 'tests'
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I finally figured it out working on another problem. The problem was that my test couldn't find an import.
It looks like you get the above error if your test fails to import. This makes sense because the test suite can't import ...
Skip List vs. Binary Search Tree
... Fraser and Harris's latest paper Concurrent programming without locks. Really good stuff if you're interested in lock-free data structures. The paper focuses on Transactional Memory and a theoretical operation multiword-compare-and-swap MCAS. Both of these are simulated in software as no hardwar...
Using forked package import in Go
...sing go modules. You could use replace directive
The replace directive allows you to supply another import path that might
be another module located in VCS (GitHub or elsewhere), or on your
local filesystem with a relative or absolute file path. The new import
path from the replace directi...
Printing object properties in Powershell
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Ugh! It still displays horizontally on the screen.... if any output goes outside your buffer it just puts .... I have a love hate with POSH
– Kolob Canyon
Jun 29 '17 at 22:50
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WebRTC - scalable live stream broadcasting / multicasting
...s a quite simple solution, which works very well: I have tested it, it is called a WebRTC gateway. Janus is a good example. It is completely open source (github repo here).
This works as follows: your broadcaster contacts the gateway (Janus) which speaks WebRTC. So there is a key negotiation: B t...
Should I use tag for icons instead of ? [closed]
...es shortness and the nice association of "i is for icon," I think it's actually the most semantic choice for an icon when a straightforward <img> tag is not practical.
1. The usage is consistent with the spec.
While it may not be what the W3 mainly had in mind, it seems to me the official sp...
What is opinionated software?
...t Microsoft tends to write "un-opinionated" frameworks. What does this actually mean?
9 Answers
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How to add a primary key to a MySQL table?
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If you want to add a primary key constraint to an existing column all of the previously listed syntax will fail.
To add a primary key constraint to an existing column use the form:
ALTER TABLE `goods`
MODIFY COLUMN `id` INT(10) UNSIGNED PRIMARY KEY AUTO_INCREMENT;
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Why use static_cast(x) instead of (int)x?
...e main reason is that classic C casts make no distinction between what we call static_cast<>(), reinterpret_cast<>(), const_cast<>(), and dynamic_cast<>(). These four things are completely different.
A static_cast<>() is usually safe. There is a valid conversion in the...