`==` 在 zsh 扩展中起什么作用？

Question

我发现了这段代码：

map () {
    eval "$initDocs"
    usage "<lambda-function> [<item>...]"
    example "'<--- \$1 --->'" a b c d
    eval "$doneDocs"
    typeset f="$1"
    shift
    map_ () {
        echo ${(e)==f}
    }
    eval "$loopNow" map_
}

我不明白${(e)f}和之间有什么区别${(e)==f}。

Answer 1

从zshexpn(1)：

${=spec}

    Perform word splitting using the rules for SH_WORD_SPLIT during the
    evaluation of spec, but regardless of whether the parameter appears
    in double quotes; if the `=' is doubled, turn it off.

换句话说，${==f}显式指定将关闭SH_WORD_SPLIT此单个扩展，无论它是否全局处于活动状态。