require-when ( if then -- )
Factor handbook » The language » Vocabulary loader

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Vocabulary
vocabs.loader

Inputs

if	a sequence of vocabulary specifiers
then	a vocabulary specifier

Outputs
None

Word description
Loads the then vocabulary if it is not loaded and all of the if vocabulary is. If some of the if vocabularies are not loaded now, but they are later, then the then vocabulary will be loaded along with the final one.

Notes
This is used to express a joint dependency of vocabularies. If vocabularies a and b use code in vocabulary c to interact, then the following line, which can be placed in a or b, expresses the dependency.

{ "a" "b" } "c" require-when

Definition

USING: arrays kernel namespaces sequences sets vocabs
vocabs.loader.private ;

IN: vocabs.loader

: require-when ( if then -- )
    over [ lookup-vocab ] all?
    [ require drop ] [
        [ drop require-when-vocabs get adjoin-all ]
        [ 2array require-when-table get push ] 2bi
    ] if ;