Expression language: Difference between revisions

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{{Short description|Computer language for creating a machine readable representation of ___domain knowledge}}

{{Merge|Unified Expression Language|date=October 2009}}

{{unsourced|date=February 2024}}

An '''expression language''' is a [[computer language]] for creating a [[machine readable]] representation of specific [[___domain knowledge]]. Examples include:

'''Expres

* double and single quotes are equivalent

* <code>object.property</code> has the same meaning as <code>object['property']</code>

*[[Advanced Boolean Expression Language]], an obsolete hardware description language for hardware descriptions

EL also liberates the programmer from having to know the particularities of how the values are actually accessed: <code>object.property</code> can mean (depending on what the <code>object</code> is) either <code>object.get("property")</code> or <code>object.getProperty("property")</code> or <code>object.getProperty()</code> etc.

*[[Data Analysis Expressions]] (DAX), an expression language developed by Microsoft and used in Power Pivot, among other places

*[[Jakarta Expression Language]], a ___domain-specific language used in Jakarta EE web applications. Formerly known as "Unified Expression Language", "Expression Language" or just "the Expression Language").

*[[Rights Expression Language]]s, machine processable language used for representing immaterial rights such as copyright and license information

{{compucomp-langsci-stub}}

Expression Language (EL) is a scripting language which allows access to Java components (JavaBeans) through JSP. Since JSP 2.0, it has been used inside JSP tags to separate Java code from JSP, and to allow easier access to Java components (than in Java code).

[[Category:ScriptingComputer languages]]

Evolution of EL occurred to make scripting easier for web-content designers who have little or practically no knowledge of the core Java Language. This scripting language makes JSP a scripting language in the true sense. Before EL, JSP consisted of some special tags like scriptlets, expressions etc. within which Java code was written explicitly. With EL the web-content designer needs only to know how to make proper calls to core Java methods and can enjoy the true scripting flavour of a scripting language.

EL is, both syntactically and semantically, similar to JavaScript expressions:

* there is no typecasting

* type conversions are usually done implicitly

* double and single quotes are equivalent

* object.property has the same meaning as object['property']

EL also liberates the programmer from having to know the particularities of how the values are actually accessed: object.property can mean (depending on what the object is) either object.get("property") or object.getProperty("property") or object.getProperty() etc.

==External links==

* [http://java.sun.com/j2ee/1.4/docs/tutorial/doc/JSPIntro7.html Java- Expression Language]

[[Category:Scripting languages]]

{{compu-lang-stub}}

[[fr:Expression Language]]

[[hu:Expression Language]]

[[pt:Linguagem de Expressão]]

[[ru:Expression Language]]