8000 Proposals: Destructuring assignment · Issue #560 · TriggerReactor/TriggerReactor · GitHub
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Sayakie opened this issue Jul 14, 2023 · 0 comments
Open

Proposals: Destructuring assignment #560

Sayakie opened this issue Jul 14, 2023 · 0 comments
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backlog Project which can't be done in short amount of time or which need more discussion. category:feature-request A feature request, i.e: not implemented / a PR. domain:suggestion A suggestion, i.e: new ideas, optimization, etc. package:core Related to share domain nor script interpreter priority:low

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Sayakie commented Jul 14, 2023

Unpacks values from arrays into distinct variables. This capability is similar to features present in languages such as JavaScript, Perl and Python.

Syntax

fruits = arrayOf("apple", "banana", "blueberry")

[apple, banana, blueberry] = fruits
#LOG apple      // Prints "apple"
#LOG banana     // Prints "banana"
#LOG blueberry  // Prints "blueberry"
balls = arrayOf("PokeBall", "DiveBall", "GreatBall", "MasterBall")

[pokeball, , , masterball] = balls
#LOG pokeball    // Prints "PokeBall"
#LOG masterball  // Prints "MasterBall"

[pokeball, ...others] = balls
#LOG others             // Prints "[DiveBall, GreatBall, MasterBall]"
#LOG others.length      // Prints "3"
#LOG others IS Array    // Prints "true"
#LOG others.getClass()  // Prints "java.lang.String[]"

Default value

Each destructured property can have a default value. The default value is used when the property is not present, or has value null.

[a, b = 2] = arrayOf(1)

#LOG b  // Prints "2"

The default value MUST be type of the right-hand side. So the following code will be thrown an exception:

[a, b = "2"] = arrayOf(1)

// Raise ParserException caused by ArrayStoreException

Rest property

As you can see in syntax section, you can end a destructuring pattern with a rest property(...rest). This pattern will store all remaining properties of the array into a new array.

[pokeball, ...others] = balls
#LOG others             // Prints "[DiveBall, GreatBall, MasterBall]"
#LOG others.length      // Prints "3"
#LOG others IS Array    // Prints "true"
#LOG others.getClass()  // Prints "java.lang.String[]"

The rest property must be last in the pattern, and must not have atrailing command.

[pokeball, ...others, ] = balls

// Raise ParserException
// Message probably like: Rest element may not have a trailing comma.
@Sayakie Sayakie added domain:suggestion A suggestion, i.e: new ideas, optimization, etc. backlog Project which can't be done in short amount of time or which need more discussion. priority:low package:core Related to share domain nor script interpreter category:feature-request A feature request, i.e: not implemented / a PR. labels Jul 14, 2023
@Sayakie Sayakie self-assigned this Jul 14, 2023
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