In the Hpricot docs (at https://github.com/hpricot/hpricot) there is a doc.search() method. The docs then go on to say "A shortcut is to use the divisor":
(doc开发者_StackOverflow/"p.posted")
It works, that's for sure, but I'm wondering, what notation is this? I have never come across it before.
Hpricot (and Nokogiri, because it support's Hpricot's shortcuts) supports two shortcut methods for "search", (/) and "at" (%).
Search means "find all occurrences of this pattern" and at means find the first occurrence. Search returns a list of nodes, while at returns a single node, which you have to keep in mind when you want to access the contents of the node.
Generally, at is good for tags or IDs you know to be unique and will not want to iterate over. Search is for things like walking over all rows in a table, or every <p> tag in a document. You can also chain from an %, which is useful for finding a particular node, then descending into it.
require 'hpricot'
html = '
<html>
<head><title>blah</title>
<body>
<div id="foo">
<p>paragraph1</p>
<p>paragraph2</p>
</div>
</body>
</head>
'
doc = Hpricot(html)
doc.at('title').inner_text # => "blah"
(doc / 'p').last.inner_text # => "paragraph2"
(doc % 'p').inner_text # => "paragraph1"
(doc % '#foo').search('p').size # => 2
Personally, I recommend Nokogiri over Hpricot. It supports all the short-cuts but is more full-featured, and very well supported.
And, the shortcuts / and % are not parts of any standard that I've seen; They're local to Hpricot, and were inherited by Nokogiri for convenience. I don't remember seeing them in Perl or Python parsers.
The notation is probably meant to evoke XPath using an overloaded / operator:
/ selects the document root (which is always the parent of the document element)
The operator needs two arguments and the LHS supplies the overloading context so you have to say
doc/"p.posted"
rather than just
/"p.posted"
/ is just a regular method, which can be called in an infix style:
>> 8 / 2 #=> 4
>> 8./ 2 #=> 4
Just define one for your own classes:
>> class Myclass
.. def /(n)
.. "Yeah" * n
.. end
.. end #=> nil
>> Myclass.new / 5 #=> "YeahYeahYeahYeahYeah"
![Interactive visualization of a graph in python [closed]](https://www.devze.com/res/2023/04-10/09/92d32fe8c0d22fb96bd6f6e8b7d1f457.gif)
加载中,请稍侯......
精彩评论