Editing Interpreter pattern (section)

===What problems can the Interpreter design pattern solve?===

Source:<ref>{{cite web|title=The Interpreter design pattern - Problem, Solution, and Applicability|url=http://w3sdesign.com/?gr=b03&ugr=proble|website=w3sDesign.com|access-date=2017-08-12}}</ref>

* A [[Backus-Naur form|grammar]] for a simple language should be defined
* so that sentences in the language can be interpreted.

When a problem occurs very often, it could be considered to represent it as a sentence in a simple language
([[Domain-specific language|Domain Specific Languages]]) so that an interpreter can solve the problem
by interpreting the sentence.

For example, when many different or complex search expressions must be specified.
Implementing (hard-wiring) them directly into a class is inflexible
because it commits the class to particular expressions and makes it impossible to specify new expressions or change existing ones independently from (without having to change) the class.