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                           XIST miscellaneous
                           ==================

URLs, pretty printing, image sizes, embedding Python code
=========================================================

   Home > Python software > ll.xist > Miscellaneous       Text · XIST

   Python softwarelist of projects

     * ll.xistAn extensible XML/HTML generator

          * ExamplesParsing/creating/modifying XML; Traversing XML
            trees
          * HowtoExplains parsing/generating XML files, XML
            transformations via XIST classes and other basic
            concepts.
          * SearchingHow to iterate through XIST trees
          * TransformationHow to transform XIST trees
          * Advanced topicsPool chaining, converter contexts,
            validation
          * MiscellaneousExplains various odds and ends of XIST

          * xscXIST core classes
          * nsPackage containing namespace modules
          * parseParsing XML
          * presentScreen output of XML trees
          * simsSimple schema validation
          * xfindTree iteration and filtering
          * cssCSS related functions
          * scriptsScripts for text conversion and creating XIST
            namespaces
          * HistoryChangeLog for XIST
          * InstallationHow to install and configure XIST
          * MigrationHow to update your code to new versions of XIST
          * Mailing listsHow to subscribe to the XIST mailing lists

     * ll.ul4cA templating language
     * ll.urlRFC 2396 compliant URLs
     * ll.makeObject oriented make replacement
     * ll.daemonForking daemon processes
     * ll.sisyphusWriting cron jobs with Python
     * ll.colorRGB color values and color model conversion
     * ll.miscMisc utility functions and classes
     * ll.orasqlUtilities for cx_Oracle
     * ll.nightshadeServe the output of Oracle functions/procedures
       with CherryPy
     * ll.scriptsScripts for UL4 template rendering and URL handling
     * AploraLogging Apache HTTP requests to an Oracle database
     * PycocoPython code coverage
     * DownloadLinks to Windows and Linux, source and binary
       distributions
     * Source codeAccess to the Mercurial repositories

                                  URLs
                                  ====

   For URL handling XIST uses the module ll.url. Refer to its
   documentation for the basic functionality (especially regarding
   the methods __div__ and relative).

   When XIST parses an XML resource it uses a so called "base" URL.
   This base URL can be passed to all parsing functions. If it isn't
   specified it defaults to the URL of the resource being parsed.
   This base URL will be prepended to all URLs that are read during
   parsing:

 >>> from ll.xist import parse
 >>> from ll.xist.ns import html
 >>> node = parse.parsestring('<img src="eggs.png"/>', base="root:spam/index.html")
 >>> print node.bytes()
 <img src="root:spam/eggs.png" />

   For publishing a base URL can be specified too. URLs will be
   published relative to this base URL with the exception of relative
   URLs in the tree. This means:

     * When you have a relative URL (e.g. #top) generated by a
       convert call, this URL will stay the same when publishing.
     * Base URLs for parsing should never be relative: Relative base
       URLs will be prepended to all relative URLs in the file, but
       this will not be reverted for publishing. In most cases the
       base URL should be a root URL when you parse local files.
     * When you parse remote web pages you can either omit the base
       argument, so it will default to the URL being parsing, so that
       links, images, etc. on the page will still point back to their
       original location, or you might want to use the empty URL
       URL() as the base, so you'll get all URLs in the page as they
       are.
     * When XIST is used as a compiler for static pages, you're going
       to read source XML files, do a conversion and write the result
       to a new target file. In this case you should probably use the
       URL of the target file for both parsing and publishing. Let's
       assume we have an URL #top in the source file. When we use the
       "real" file names for parsing and publishing like this:

 node = parse.parsefile("spam.htmlxsc", base="root:spam.htmlxsc")
 node = node.conv()
 node.write(open("spam.html", "wb"), base="root:spam.html")

       the following will happen: The URL #top will be parsed as
       root:spam.htmlxsc#top. After conversion this will be written
       to spam.html relative to the URL root:spam.html, which results
       in spam.html#top, which works, but is not what you want.

       When you use root:spam.html both for parsing and publishing,
       #top will be written to the target file as expected.

                          Pretty printing XML
                          ===================

   The method pretty can be used for pretty printing XML. It returns
   a new version of the node, with additional white space between the
   elements:

 from ll.xist.ns import html
 node = html.html(
 ·  html.head(
 ·  ·  html.title(u"foo"),
 ·  ),
 ·  html.body(
 ·  ·  html.div(
 ·  ·  ·  html.h1(u"The ", html.em(u"foo"), u" page!"),
 ·  ·  ·  html.p(u"Welcome to the ", html.em(u"foo"), u" page."),
 ·  ·  ),
 ·  ),
 )

 print node.pretty().bytes()

   This will print:

 <html>
 ·  <head>
 ·  ·  <title>foo</title>
 ·  </head>
 ·  <body>
 ·  ·  <div>
 ·  ·  ·  <h1>The <em>foo</em> page!</h1>
 ·  ·  ·  <p>Welcome to the <em>foo</em> page.</p>
 ·  ·  </div>
 ·  </body>
 </html>

   Element content will only be modified if it doesn't contain Text
   nodes, so mixed content will not be touched.

             Automatic generation of image size attributes
             =============================================

   The module ll.xist.ns.htmlspecials contains an element autoimg
   that extends ll.xist.ns.html.img. When converted to HTML via the
   convert method the size of the image will be determined and the
   height and width attributes will be set accordingly (if those
   attributes are not set already).

                         Embedding Python code
                         =====================

   It's possible to embed Python code into XIST XML files. For this
   XIST supports two new processing instructions: pyexec and pyeval
   (in the module ll.xist.ns.code). The content of pyexec will be
   executed when the processing instruction node is converted.

   The result of a call to convert for a pyeval processing
   instruction is whatever the Python code in the content returns.
   The processing instruction content is treated as the body of a
   function, so you can put multiple return statements there. The
   converter is available as the parameter converter inside the
   processing instruction. For example, consider the following XML
   file:

 <?pyexec
 ·  # sum
 ·  def gauss(top=100):
 ·  ·  sum = 0
 ·  ·  for i in xrange(top+1):
 ·  ·  ·  sum += i
 ·  ·  return sum
 ?>
 <b><?pyeval return gauss()?></b>

   Parsing this file and calling convert results in the following:

 <b>5050</b>