54 lines
2.0 KiB
Factor
54 lines
2.0 KiB
Factor
USING: help.markup help.syntax ;
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IN: values
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ARTICLE: "values" "Global values"
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"Usually, dynamically-scoped variables subsume global variables and are sufficient for holding global data. But occasionally, for global information that's calculated just once and must be accessed more rapidly than a dynamic variable lookup can provide, it's useful to use the word mechanism instead, and set a word to the appropriate value just once. The " { $vocab-link "values" } " vocabulary implements " { $emphasis "values" } ", which abstract over this concept. To create a new word as a value, use the following syntax:"
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{ $subsections POSTPONE: VALUE: }
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"To get the value, just call the word. The following words manipulate values:"
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{ $subsections
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get-value
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set-value
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POSTPONE: to:
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change-value
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} ;
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ABOUT: "values"
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HELP: VALUE:
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{ $syntax "VALUE: word" }
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{ $values { "word" "a word to be created" } }
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{ $description "Creates a value on the given word, initializing it to hold " { $snippet "f" } ". To get the value, just run the word. To set it, use " { $link POSTPONE: to: } "." }
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{ $examples
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{ $example
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"USING: values math prettyprint ;"
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"IN: scratchpad"
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"VALUE: x"
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"2 2 + to: x"
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"x ."
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"4"
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}
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} ;
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HELP: get-value
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{ $values { "word" "a value word" } { "value" "the contents" } }
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{ $description "Gets a value. This should not normally be used, unless the word is not known until runtime." } ;
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HELP: set-value
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{ $values { "value" "a new value" } { "word" "a value word" } }
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{ $description "Sets a value word." } ;
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HELP: to:
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{ $syntax "... to: value" }
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{ $values { "word" "a value word" } }
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{ $description "Sets a value word." }
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{ $notes
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"Note that"
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{ $code "foo to: value" }
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"is just sugar for"
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{ $code "foo \\ value set-value" }
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} ;
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HELP: change-value
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{ $values { "word" "a value word" } { "quot" { $quotation "( oldvalue -- newvalue )" } } }
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{ $description "Changes the value using the given quotation." } ;
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