SEP-006: Rename of Selectors to Extractors
| SEP | 6 |
| Title | Extractors |
| Author | Ismael Carnales and a bunch of rabid mice |
| Created | 2009-07-28 |
| Status | Obsolete (discarded) |
Abstract
This SEP proposes a more meaningful naming of XPathSelectors or "Selectors" and their x method.
Motivation
When you use Selectors in Scrapy, your final goal is to "extract" the data that you've selected, as the XPath Selectors documentation says (bolding by me):
"When you’re scraping web pages, the most common task you need to perform is to extract data from the HTML source."
...
"Scrapy comes with its own mechanism for extracting data. They’re called XPath selectors (or just “selectors”, for short) because they “select” certain parts of the HTML document specified by XPath expressions."
...
"To actually extract the textual data you must call the selector extract() method, as follows"
...
"Selectors also have a re() method for extracting data using regular expressions."
...
"For example, suppose you want to extract all <p> elements inside <div> elements. First you get would get all <div> elements"
Rationale
As and there is no Extractor object in Scrapy and what you want to finally perform with Selectors is extracting data, we propose the renaming of Selectors to Extractors. (In Scrapy for extracting you use selectors is really weird :) )
Additional changes
As the name of the method for performing selection (the x method) is not descriptive nor mnemotechnic enough and clearly clashes with extract method (x sounds like a short for extract in english), we propose to rename it to select, sel (is shortness if required), or xpath after lxml's xpath method
Bonus (ItemBuilder)
After this renaming we propose also renaming ItemBuilder to ItemExtractor, because the ItemBuilder/Extractor will act as a bridge between a set of Extractors and an Item and because it will literally "extract" an item from a webpage or set of pages.
References
- XPath Selectors (http://doc.scrapy.org/topics/selectors.html)
- XPath and XSLT with lxml (http://codespeak.net/lxml/xpathxslt.html)
