There are seven different column types that can be used within a GridView.
<asp:GridView ID="GridView1" runat="server">
<Columns>
...
</Columns>
</asp:GridView>
BoundField:
<asp:BoundField DataField="EmployeeID" Heade...
When is an IComparer<T> a subtype of a different IComparer<T1>? When T1 is a subtype of T. IComparer is contravariant in its T parameter, which means that IComparer's subtype relationship goes in the opposite direction as T's.
class Animal { /* ... */ }
class Dog : Animal { /* ... */ }...
let x = true
match x with
| true -> printfn "x is true"
yields a warning
C:\Program Files (x86)\Microsoft VS Code\Untitled-1(2,7): warning FS0025: Incomplete pattern matches on this expression. For example, the value 'false' may indicate a case not covered by the pattern(s).
...
type Person = {
Age : int
PassedDriversTest : bool }
let someone = { Age = 19; PassedDriversTest = true }
match someone.PassedDriversTest with
| true when someone.Age >= 16 -> printfn "congrats"
| true -> printfn "wait until you are 16"
| false -> p...
compile built-in function can be used to precompile an expression to a code object; this code object can then be passed to eval. This will speed up the repeated executions of the evaluated code. The 3rd parameter to compile needs to be the string 'eval'.
>>> code = compile('a * b + c', '&l...
As the static keyword is used for accessing fields and methods without an instantiated class, it can be used to declare constants for use in other classes. These variables will remain constant across every instantiation of the class. By convention, static variables are always ALL_CAPS and use unders...
If you want to mock AR that doesn't try to connect to database you can do it in the following way (if using PHPUnit):
$post = $this->getMockBuilder('\app\model\Post')
->setMethods(['save', 'attributes'])
->getMock();
$post->method('save')->willReturn(true);
$post->meth...
The control directive is used with the user controls and appears in the user control (.ascx) files.
The basic syntax of Control directive is:
<%@ Control Language="C#" EnableViewState="false" %>
The attributes of the Control directive are:
AttributesDescriptionAutoEv...
To add annotations, hints, or exclude some code from being executed JavaScript provides two ways of commenting code lines
Single line Comment //
Everything after the // until the end of the line is excluded from execution.
function elementAt( event ) {
// Gets the element from Event coordinate...
Record syntax can be used with newtype with the restriction that there is exactly one constructor with exactly one field. The benefit here is the automatic creation of a function to unwrap the newtype. These fields are often named starting with run for monads, get for monoids, and un for other typ...
Differences in subsetting syntax
A data.table is one of several two-dimensional data structures available in R, besides data.frame, matrix and (2D) array. All of these classes use a very similar but not identical syntax for subsetting, the A[rows, cols] schema.
Consider the following data stored i...
Using Kestrel you can specify port using next approaches:
Defining ASPNETCORE_URLS environment variable.
Windows
SET ASPNETCORE_URLS=https://0.0.0.0:5001
OS X
export ASPNETCORE_URLS=https://0.0.0.0:5001
Via command line passing --server.urls parameter
dotnet run --server.urls=http...
If you have a string that contains Python literals, such as strings, floats etc, you can use ast.literal_eval to evaluate its value instead of eval. This has the added feature of allowing only certain syntax.
>>> import ast
>>> code = """(1, 2, {'foo': 'bar'})"...
It is not possible to use eval or exec to execute code from untrusted user securely. Even ast.literal_eval is prone to crashes in the parser. It is sometimes possible to guard against malicious code execution, but it doesn't exclude the possibility of outright crashes in the parser or the tokenizer....
With ASP.NET Core 1.0, the MVC and Web API framework have been merged into one framework called ASP.NET Core MVC. This is a good thing, since MVC and Web API share a lot of functionality, yet there always were subtle differences and code duplication.
However, merging these two into framework one ...
The case modifier causes the Scala compiler to automatically generate common boilerplate code for the class. Implementing this code manually is tedious and a source of errors. The following case class definition:
case class Person(name: String, age: Int)
... will have the following code automati...
CLP(FD) constraints are provided by all serious Prolog implementations. They allow us to reason about integers in a pure way.
?- X #= 1 + 2.
X = 3.
?- 5 #= Y + 2.
Y = 3.
Destructuring also gives you the ability to interpret a sequence as a map:
(def my-vec [:a 1 :b 2])
(def my-lst '("smthg else" :c 3 :d 4))
(let [[& {:keys [a b]}] my-vec
[s & {:keys [c d]} my-lst]
(+ a b c d)) ;= 10
It is useful for defining functions with named p...
CLP(FD) constraints are completely pure relations. They can be used in all directions for declarative integer arithmetic:
?- X #= 1+2.
X = 3.
?- 3 #= Y+2.
Y = 1.
