Tutorial by Examples: u

This is a snippet of master report. The datasource is passed to the subreport with help of net.sf.jasperreports.engine.data.JRBeanCollectionDataSource constructor <field name="someFieldWithList" class="java.util.List"/> <!-- ...... --> <subreport> <r...

The CLOS MOP provides the hook slot-value-using-class, that is called when a slot is value is accessed, read or modified. Because we only care for modifications in this case we define a method for (setf slot-value-using-class). (defclass document () ((id :reader id :documentation "A hash co...

Classification in Machine Learning is the problem that identifies to which set of categories does a new observation belong. Classification falls under the category of Supervised Machine Learning. Any algorithm that implements classification is known as classifier The classifiers supported in P...

Every custom loader must directly or indirectly extend the java.lang.ClassLoader class. The main extension points are the following methods: findClass(String) - overload this method if your classloader follows the standard delegation model for class loading. loadClass(String, boolean) - overloa...

Clustering is about grouping similar objects together. It is widely used for pattern recognition. Clustering comes under unsupervised machine learning, therefore there is no training needed. PHP-ML has support for the following clustering algorithms k-Means dbscan k-Means k-Means separates ...

The Java language allows you to use new to create instances Integer, Boolean and so on, but it is generally a bad idea. It is better to either use autoboxing (Java 5 and later) or the valueOf method. Integer i1 = new Integer(1); // BAD Integer i2 = 2; // BEST (autoboxing)...

We're all used to the while syntax, that executes its body while the condition is evaluated to true. What if we want to implement an until loop, that executes a loop until the condition is evaluated to true? In Julia, we can do this by creating a @until macro, that stops to execute its body when th...

A statement is constructed with a function such as sqlite3_prepare_v2(). A prepared statement object must be cleaned up with sqlite3_finalize(). Do not forget this in case of an error. If parameters are used, set their values with the sqlite3_bind_xxx() functions. The actual execution happens whe...

A SELECT query is executed like any other statement. To read the returned data, call sqlite3_step() in a loop. It returns: SQLITE_ROW: if the data for the next row is available, or SQLITE_DONE: if there are no more rows, or any error code. If a query does not return any rows, the very first...

gnu-cobol is available via the homebrew system. Open a terminal window from /Applications/Utilities/Terminal or use the keypress Command+Space and type "Terminal". If you do not have the homebrew system installed, add it by typing, or copying and pasting into your terminal: ruby -e &quo...

PHP has built in function pcntl_fork for creating child process. pcntl_fork is same as fork in unix. It does not take in any parameters and returns integer which can be used to differentiate between parent and child process. Consider the following code for explanation <?php // $pid is the P...

Interprocess communication allows programmers to communicate between different processes. For example let us consider we need to write an PHP application that can run bash commands and print the output. We will be using proc_open , which will execute the command and return a resource that we can com...

Standalone Common Lisp binaries can be built with buildapp. Before we can use it to generate binaries, we need to install and build it. The easiest way I know how is using quicklisp and a Common Lisp (this example uses [sbcl], but it shouldn't make a difference which one you've got). $ sbcl Thi...

The simplest possible binary you could build Has no dependencies Takes no command line arguments Just writes "Hello world!" to stdout After you've built buildapp, you can just... $ buildapp --eval '(defun main (argv) (declare (ignore argv)) (write-line "Hello, world!"))'...

A more realistic example involves a project you're building with multiple files on disk (rather than an --eval option passed to buildapp), and some dependencies to pull in. Because arbitrary things can happen during the finding and loading of asdf systems (including loading other, potentially unrel...

HTML Form Use a file type input and the browser will provide a field that lets the user select a file to upload. Only forms with the post method can send file data. Make sure to set the form's enctype=multipart/form-data attribute. Otherwise the file's name will be sent but not the file's data...

Uploaded files are available in request.files, a MultiDict mapping field names to file objects. Use getlist — instead of [] or get — if multiple files were uploaded with the same field name. request.files['profile'] # single file (even if multiple were sent) request.files.getlist('charts') # li...

It may be useful to have one catch-all view where you handle complex logic yourself based on the path. This example uses two rules: The first rule specifically catches / and the second rule catches arbitrary paths with the built-in path converter. The path converter matches any string (including sl...

An enumerations value in no way needs to be unique: #include <stdlib.h> /* for EXIT_SUCCESS */ #include <stdio.h> /* for printf() */ enum Dupes { Base, /* Takes 0 */ One, /* Takes Base + 1 */ Two, /* Takes One + 1 */ Negative = -1, AnotherZero /* Takes Negativ...

We can create it by two way. First from database properties designer mode: And by sql scripts: USE master; GO -- Create the database with the default data -- filegroup and a log file. Specify the -- growth increment and the max size for the -- primary data file. CREATE DATABASE TestDB ON...