String interpolation: Difference between revisions

Revision as of 22:40, 9 May 2023

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In [[computer programming]], '''string interpolation''' (or '''variable interpolation''', '''variable substitution''', or '''variable expansion''') is the process of evaluating a [[string literal]] containing one or more [[Form (document)#Placeholders|placeholders]], yielding a result in which the placeholders are replaced with their corresponding values. It is a form of simple [[Template processor|template processing]]<ref>"[http://www.cs.usfca.edu/~parrt/papers/mvc.templates.pdf Enforcing Strict Model-View Separation in Template Engines]", T. Parr (2004), WWW2004 conference.</ref> or, in formal terms, a form of [[quasi-quotation]] (or logic [[Substitution (logic)|substitution]] interpretation). The placeholder may be a variable name, or in some languages an arbitrary expression, in either case evaluated in the current [[Scope (computer science)|context]].

String interpolation is an alternative to building string via [[concatenation]], which requires repeatedrepeat quoting and unquoting;<ref>{{Cite web|url=http://perlmeme.org/howtos/using_perl/interpolation.html|title = Interpolation in Perl |quote="This is much tidier than repeatedrepeat uses of the '.' concatenation operator."}}</ref> or substituting into a [[printf format string]], where the variable is far from where it is used. Compare:

<syntaxhighlight lang="python">

apples = 4