Subexpression
A subexpression is an expression or pattern nested within a larger expression or pattern as one of its components.
Building User-Friendly DSLs
An expression contained within another expression as one of its component expressions.
- How it is used
- Uses contained expressions to represent detailed DSL calculations and decisions.
- How deep it goes
- Explains recursive evaluation, operand structure, AST construction, and compositionality without parser implementation details.
- Examples
- Uses discount of rental price before discount, `1 + 2 * 3`, and `1 + 2 * (3 + 4)`.
- What you can do after
- Build it from scratch by nesting operand AST objects and evaluating them recursively according to operator rules.
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Learn PowerShell in a Month of Lunches: Fourth Edition, Covers Windows, Linux, and macOS
A subexpression is an expression nested within a larger expression and evaluated as one operand or component.
- How it is used
- Embeds evaluated PowerShell commands in strings and groups conditions for logical comparison.
- How deep it goes
- Defines subexpressions and demonstrates their evaluation, but stops short of deeper language implementation details.
- Examples
- Uses process collections, indexed properties, repeated regex groups, and Boolean comparisons as concrete examples.
- What you can do after
- Apply it via PowerShell to place command results in strings and group conditions for readable Boolean tests.
Related concepts
- boolean operationused by · A Boolean operation combines or transforms truth-valued inputs according to logical rules to produce a truth-valued result.
- quotation marksuses · Double quotation marks are paired punctuation characters used to delimit quoted text and, in programming languages, string literals.
- type computationused by · The process of determining the type produced by an expression from its syntax, operands, and context.
- quantifierconfigures · A regular-expression quantifier is syntax that specifies how many times a preceding pattern element may or must match.
- regular expressionpart of · A formal pattern notation that describes sets of strings and enables text to be matched, searched, extracted, or transformed.
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