In computer programming, boilerplate code or boilerplate refers to sections of code that have to be included in many places with little or no alteration. It is often used when referring to languages that are considered verbose, i.e. the programmer must write a lot of code to do minimal jobs.
The need for boilerplate can be reduced through high-level mechanisms such as metaprogramming (which has the computer automatically write the needed boilerplate code or insert it at compile time), convention over configuration (which provides good default values, reducing the need to specify program details in every project) and model-driven engineering (which uses models and model-to-code generators, eliminating the need for boilerplate manual code).
Video Boilerplate code
Origin
The term arose from the newspaper business. Columns and other pieces that were distributed by print syndicates were sent to subscribing newspapers in the form of prepared printing plates. Because of their resemblance to the metal plates used in the making of boilers, they became known as "boiler plates", and their resulting text - "boilerplate text". As the stories that were distributed by ready plates way were usually "fillers" rather than "serious" news, the term became synonymous with unoriginal, repetitive text.
A related term is bookkeeping code, referring to code that is not part of the business logic but is interleaved with it in order to keep data structures updated or handle secondary aspects of the program.
Maps Boilerplate code
Preamble
One form of boilerplate consists of declarations which, while not part of the program logic or the language's essential syntax, are added to the start of a source file as a matter of custom. The following Perl example demonstrates boilerplate:
The first line is a shebang, which identifies the file as a Perl script that can be executed directly on the command line (on Unix/Linux systems.) The other two are pragmas turning on warnings and strict mode, which are mandated by fashionable Perl programming style.
This next example is a C/C++ programming language boilerplate, #include guard.
This sets up, and checks, a global flag to tell the compiler whether the file myinterface.h has already been included. As many interdepending files may be involved in the compilation of a module, this avoids processing the same header multiple times (which would lead to errors due to multiple definitions with the same name).
In object-oriented programming
In object-oriented programs, classes are often provided with methods for getting and setting instance variables. The definitions of these methods can frequently be regarded as boilerplate. Although the code will vary from one class to another, it is sufficiently stereotypical in structure that it would be better generated automatically than written by hand. For example, in the following Java class representing a pet, almost all the code is boilerplate except for the declarations of Pet, name and owner:
Most of the boilerplate in this example exists to provide encapsulation. If the variables name and owner were declared as public, the accessor and mutator methods would not be needed.
To reduce the amount of boilerplate, many frameworks have been developed, e.g. Lombok for Java. The same code as above is auto-generated by Lombok using Java annotations, which is a form of metaprogramming:
In some other programming languages it may be possible to achieve the same thing with less boilerplate, when the language has built-in support for such common constructs. For example, the equivalent of the above Java code can be expressed in Scala using just one line of code:
Or in C# using Automatic Properties with compiler generated backing fields:
HTML
In HTML, the following boilerplate is used as a basic empty template and is present in most web pages:
The WHATWG HTML Living Standard defines that the <html>, <head> and <body> tags may be safely omitted under most circumstances. The <meta charset="UTF-8"> tag may also be omitted if the Web server is properly configured to send the character encoding along with the content type. Google's HTML/CSS style guide recommends that all optional tags be omitted, resulting in a much more compact boilerplate:
See also
References
Source of the article : Wikipedia
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