douangzhao4108 2018-06-02 16:29
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从递归函数返回数据?

I am slightly confused how do I refactor to return array data instead storing $this->data in the makeData() method.

For example:

private function makeData($cat, $itemCatId)
{
    $parentCat = $cat[$cat[$itemCatId]->parent_id];

     $this->data[] = $parentCat;

    if (!is_null($parentCat->parent_id)) {
        $this->makeData($cat, $parentCat->id);
    }
}

Usage

foreach($items as $item) {
 $this->data = []
 $this->makeData($cat, $item->id);

 // Then do something with `$this->data`
}

Then do something with $this->data

It seem this look like a code smell, in there a way to return data from makeData() when the Recursive is completed? For example:

foreach($items as $item) {
 $data = $this->makeData($cat, $item->id);

 // Then do something with `$data`
}
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1条回答 默认 最新

  • douchen5971 2018-06-02 17:28
    关注

    You dont need recursion in this simple case. You can change point of reference in loop:

    function ancestors($data, $id) {
        $result = [];
        while ($id = $data[$id]->parent_id ?? false) {
            $result[] = $data[$id];
        }
        return $result;
    }
    

    Recursion would require dragging result and appending to it or array merging/unshifting (since its only one value at a time):

    function ancestors($data, $id) {
        $result = [];
        if ($id = $data[$id]->parent_id ?? false) {
            $result = parents($data, $id);
            array_unshift($result, $data[$id]);
        }
    
        return $result;
    }
    

    If reversed order doesn't bother you you might push $data[$id] to the end of recursively produced list as well.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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