52 lines
2.0 KiB
Factor
52 lines
2.0 KiB
Factor
USING: help.markup help.syntax ;
|
|
IN: values
|
|
|
|
ARTICLE: "values" "Global values"
|
|
"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:"
|
|
{ $subsection POSTPONE: VALUE: }
|
|
"To get the value, just call the word. The following words manipulate values:"
|
|
{ $subsection get-value }
|
|
{ $subsection set-value }
|
|
{ $subsection POSTPONE: to: }
|
|
{ $subsection change-value } ;
|
|
|
|
ABOUT: "values"
|
|
|
|
HELP: VALUE:
|
|
{ $syntax "VALUE: word" }
|
|
{ $values { "word" "a word to be created" } }
|
|
{ $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: } "." }
|
|
{ $examples
|
|
{ $example
|
|
"USING: values math prettyprint ;"
|
|
"IN: scratchpad"
|
|
"VALUE: x"
|
|
"2 2 + to: x"
|
|
"x ."
|
|
"4"
|
|
}
|
|
} ;
|
|
|
|
HELP: get-value
|
|
{ $values { "word" "a value word" } { "value" "the contents" } }
|
|
{ $description "Gets a value. This should not normally be used, unless the word is not known until runtime." } ;
|
|
|
|
HELP: set-value
|
|
{ $values { "value" "a new value" } { "word" "a value word" } }
|
|
{ $description "Sets a value word." } ;
|
|
|
|
HELP: to:
|
|
{ $syntax "... to: value" }
|
|
{ $values { "word" "a value word" } }
|
|
{ $description "Sets a value word." }
|
|
{ $notes
|
|
"Note that"
|
|
{ $code "foo to: value" }
|
|
"is just sugar for"
|
|
{ $code "foo \\ value set-value" }
|
|
} ;
|
|
|
|
HELP: change-value
|
|
{ $values { "word" "a value word" } { "quot" { $quotation "( oldvalue -- newvalue )" } } }
|
|
{ $description "Changes the value using the given quotation." } ;
|