Tutorial by Examples: me

Lets say we have a class as (defclass person () (name email age)) To obtain the names of the slots of the class we use the function class-slots. This can be found in the closer-mop package, provided by the closer-mop system. To load it the running lisp image we use (ql:quickload :closer-mop)....

itertools.combinations will return a generator of the k-combination sequence of a list. In other words: It will return a generator of tuples of all the possible k-wise combinations of the input list. For Example: If you have a list: a = [1,2,3,4,5] b = list(itertools.combinations(a, 2)) print ...

Some HTTP requests may contain a message body. This is additional data that the server will use to process the request. Message bodies are most often used in POST or PATCH and PUT requests, to provide new data that the server should apply to a resource. Requests that include a message body should a...

Generic parameters can also be bound to more than one type using the T extends Type1 & Type2 & ... syntax. Let's say you want to create a class whose Generic type should implement both Flushable and Closeable, you can write class ExampleClass<T extends Flushable & Closeable> { }...

To make a class a subclass of another class, use parent pragma: package Point; use strict; ... 1; package Point2D; use strict; use parent qw(Point); ... 1; package Point3D; use strict; use parent qw(Point); ... 1; Perl allows for multiple inheritance: package Point2D; use stri...

In Perl, the difference between class (static) and object (instance) methods is not so strong as in some other languages, but it still exists. The left operand of the arrow operator -> becomes the first argument of the method to be called. It may be either a string: # the first argument of new ...

To get the previous element you can use the .prev() method. <ul> <li>Mark</li> <li class="anna">Anna</li> <li>Paul</li> </ul> If you are standing on the "Anna" element and you want to get the previous element, &q...

The dir() function can be used to get a list of the members of a class: dir(Class) For example: >>> dir(list) ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__...

ISO/ANSI SQL: SELECT Id, Col1 FROM TableName ORDER BY Id OFFSET 20 ROWS MySQL: SELECT * FROM TableName LIMIT 20, 42424242424242; -- skips 20 for take use very large number that is more than rows in table Oracle: SELECT Id, Col1 FROM (SELECT Id, Col1, row_num...

ISO/ANSI SQL: SELECT Id, Col1 FROM TableName ORDER BY Id OFFSET 20 ROWS FETCH NEXT 20 ROWS ONLY; MySQL: SELECT * FROM TableName LIMIT 20, 20; -- offset, limit Oracle; SQL Server: SELECT Id, Col1 FROM (SELECT Id, Col1, row_number() over (order by Id) RowNumbe...

DESCRIBE and EXPLAIN are synonyms. DESCRIBE on a tablename returns the definition of the columns. DESCRIBE tablename; Exmple Result: COLUMN_NAME COLUMN_TYPE IS_NULLABLE COLUMN_KEY COLUMN_DEFAULT EXTRA id int(11) NO PRI 0 ...

With the case statement you can match values against one variable. The argument passed to case is expanded and try to match against each patterns. If a match is found, the commands upto ;; are executed. case "$BASH_VERSION" in [34]*) echo {1..4} ;; *) seq -s" ...

The following are examples of how to install MIT/GNU Scheme: Debian/Ubuntu installation: sudo apt-get install mit-scheme Manual installation: Download the Unix binary directly from the GNU Project, then follow the instructions from the official webpage: # Unpack the tar file tar xzf mit-sche...

If your project doesn't have README.md, GitHub may parse README.rdoc to display details. If it has both, it will use README.md, silently ignoring rdoc. A README file may include- Project Title Describe briefly about your project. You may also provide project's website link, badges, community ...

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To add a method to a button, first create an action method: Objective-C -(void) someButtonAction{ NSLog(@"Button is tapped"); } Swift func someButtonAction() { print("Button is tapped") } Now to add this action method to your button, you have to wri...

Import the CoreLocation module in your classes that use CoreLocation functionality. //Swift import CoreLocation //Objective-C #import <CoreLocation/CoreLocation.h>

Observe the notifications UIKeyboardWillShowNotification and UIKeyboardWillHideNotification, update the scrollView content insets according to keyboard height, then scroll to the focused control. - (void)viewDidLoad { [super viewDidLoad]; // register for keyboard notifications [[...

Session cookies parameters are important both if you have a need to maintain session while getting from one subdomain to another or when, in contrary, you host backend app under /admin URL and want handle session separately. $config = [ // ... 'components' => [ // ... ...

Element and attribute names live in namespaces that are URIs. Namespaces are bound to prefixes that are used in the actual element and attribute names, which are called QNames. This document binds a namespace to the prefix prefix and defines a default namespace, bound with the absence of prefix. &...