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dynamic_cast and static_cast in C++
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Here's a rundown on static_cast<> and dynamic_cast<> specifically as they pertain to pointers. This is just a 101-level rundown, it does not cover all the intricacies.
static_cast< Type* >(ptr)
This takes the pointer in ptr and tries to safely cast it to a pointer of type Type...
Is git's semi-secret empty tree object reliable, and why is there not a symbolic name for it?
...0 +0000" GIT_COMMITTER_DATE="Thu, 01 Jan 1970 00:00:00 +0000" git commit --allow-empty -m 'Initial commit'
Will give you:
(See the tree SHA1?)
You can even rebase your existing history on top of that empty commit (see "git: how to insert a commit as the first, shifting all the others?")
In bo...
Running Bash commands in Python
... are commonly overlooked.
Prefer subprocess.run() over subprocess.check_call() and friends over subprocess.call() over subprocess.Popen() over os.system() over os.popen()
Understand and probably use text=True, aka universal_newlines=True.
Understand the meaning of shell=True or shell=False and how...
Transaction isolation levels relation with locks on table
...B just executes a SELECT statement to read data. C reads and updates data. All these process work on the same table T.
READ UNCOMMITTED - no lock on the table. You can read data in the table while writing on it. This means A writes data (uncommitted) and B can read this uncommitted data and use it...
ASP.NET MVC View Engine Comparison
...ferent problem from "tag soup" referenced above. Where the server tags actually provide structure around server and non-server code, Razor confuses HTML and server code, making pure HTML or JS development challenging (see Con Example #1) as you end up having to "escape" HTML and / or JavaScript tags...
A variable modified inside a while loop is not remembered
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@AvinashYadav The problem isn't really related to while loop or for loop; rather the use of subshell i.e., in cmd1 | cmd2, cmd2 is in a subshell. So if a for loop is executed in a subshell, the unexpected/problematic behaviour will be exhibited.
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Create Directory if it doesn't exist with Ruby
... ["foo/bar"]
Edit2: you do not have to use FileUtils, you may do system call (update from @mu is too short comment):
> system 'mkdir', '-p', 'foo/bar' # worse version: system 'mkdir -p "foo/bar"'
=> true
But that seems (at least to me) as worse approach as you are using external 'tool' wh...
Mockito: Inject real objects into private @Autowired fields
...njectMocks
private Demo demo;
/* ... */
}
Mockito will consider all fields having @Mock or @Spy annotation as potential candidates to be injected into the instance annotated with @InjectMocks annotation. In the above case 'RealServiceImpl' instance will get injected into the 'demo'
For m...
dynamically add and remove view to viewpager
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After figuring out which ViewPager methods are called by ViewPager and which are for other purposes, I came up with a solution. I present it here since I see a lot of people have struggled with this and I didn't see any other relevant answers.
First, here's my adapter; ...
Devise form within a different controller
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As Andres says, the form calls helpers which are specified by Devise and so aren't present when you access a Devise form from a non-Devise controller.
To get around this, you need to add the following methods to the helper class of the controller you...