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Why are arrays covariant but generics are invariant?
...to implement functions of type
boolean equalArrays (Object[] a1, Object[] a2);
void shuffleArray(Object[] a);
However, if array types were treated as invariant, it would only be possible to call these functions on an array of exactly the type Object[]. One could not, for example, shuffle an a...
Why does C++ require a user-provided default constructor to default-construct a const object?
...A() {} //this makes non-POD
};
nonPOD_A a1; //initialized
const nonPOD_A a2; //initialized
Note the difference between POD and non-POD.
User-defined constructor is one way to make the class non-POD. There are several ways you can do that.
struct nonPOD_B
{
virtual void f() {} //virtual fu...
Business logic in MVC [closed]
...he other hand is responsible to receive user input and decide what to do.
A2: A Business Rule is part of Business Logic. They have a has a relationship. Business Logic has Business Rules.
Take a look at Wikipedia entry for MVC. Go to Overview where it mentions the flow of MVC pattern.
Also look a...
What does this square bracket and parenthesis bracket notation mean [first1,last1)?
...lute element. i.e. Using subscript notation to denote the index:
a1 = 2
a2 = 3
:
a10 = 29
Some programming languages, in contradistinction, would refer to the first element as the zero'th relative element.
a[0] = 2
a[1] = 3
:
a[9] = 29
Since the array indexes are in the range [0,N-1] then f...
SQL Server CTE and recursion example
...hose employee details will come those who are subordinate of that manager
A2:
Does this code answer your question?
--------------------------------------------
-- Synthesise table with non-recursive CTE
--------------------------------------------
;WITH Employee (ID, Name, MgrID) AS
(
SELECT...
How to send a “multipart/form-data” with requests in python?
...p://httpbin.org/post', files=files).prepare().body.decode('utf8'))
--bb3f05a247b43eede27a124ef8b968c5
Content-Disposition: form-data; name="foo"; filename="foo"
bar
--bb3f05a247b43eede27a124ef8b968c5--
>>> files = {'foo': (None, 'bar')}
>>> print(requests.Request('POST', 'http://h...
Any reason why scala does not explicitly support dependent types?
...implicitly[foo1.Bar =:= foo2.Bar] // Not OK: unequal types
<console>:11: error: Cannot prove that foo1.Bar =:= foo2.Bar.
implicitly[foo1.Bar =:= foo2.Bar]
In my view, the above should be enough to answer the question "Is Scala a dependently typed language?" in the positive: it'...
Which characters make a URL invalid?
...t characters are reserved for URLs in this format: http://[2001:db8:85a3::8a2e:370:7334]/foo/bar (i.e. an IPv6 literal instead of a host name)
It's worth reading RFC 3986 carefully if you want to understand the issue fully.
...
source of historical stock data [closed]
...day, m for month, y for yearly
The complete list of parameters:
a Ask
a2 Average Daily Volume
a5 Ask Size
b Bid
b2 Ask (Real-time)
b3 Bid (Real-time)
b4 Book Value
b6 Bid Size
c Change & Percent Change
c1 Change
c3 Commission
c6 Change (Real-time)
c8 After Hours Change (Real-t...
What do the terms “CPU bound” and “I/O bound” mean?
...h CPU: Intel Core i7-7820HQ CPU (4 cores / 8 threads), RAM: 2x Samsung M471A2K43BB1-CRC (2x 16GiB) I get results like this:
Plot data.
Note that there is a lot of variance between run however. But I can't increase the array size much further since I'm already at 8GiB, and I'm not in the mood for st...