Following the recent PhillyPUG meetup I was trying to install scrapy on an old MacBook Pro running OS X 10.6 (Snow Leopard) and ran into a number of problems with the lxml dependency. This is the parser used to extract data from pages that scrapy downloads so you are not going to get very far without it.

It seems that the compilation problems experienced when installing with pip result from an attempt to build a universal binary. If you have Xcode 4 installed then you lose some of this capability and need to make sure that the correct architecture is specified.

Architecture Fix

Setting the architecture is something you can do in your bash profile, executing it under a new bash ensures that the build script picks it up.

sudo bash
export ARCHFLAGS='-arch i386 -arch x86_64'
pip install lxml # test it
pip install scrapy --upgrade # fix the failed scrapy install

Original Error

brianly$ sudo pip install lxml --upgrade
Downloading/unpacking lxml
  Downloading lxml-2.3.tar.gz (3.2Mb): 3.2Mb downloaded
  Running setup.py egg_info for package lxml
    Building lxml version 2.3.
    Building without Cython.
    Using build configuration of libxslt 1.1.24
    warning: no previously-included files found matching '*.py'
Installing collected packages: lxml
  Found existing installation: lxml 2.2.2
    Uninstalling lxml:
      Successfully uninstalled lxml
  Running setup.py install for lxml
    Building lxml version 2.3.
    Building without Cython.
    Using build configuration of libxslt 1.1.24
    building 'lxml.etree' extension
    gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch ppc -arch x86_64 -pipe -I/usr/include/libxml2 -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/lxml/lxml.etree.c -o build/temp.macosx-10.6-universal-2.6/src/lxml/lxml.etree.o -w -flat_namespace
    /usr/libexec/gcc/powerpc-apple-darwin10/4.2.1/as: assembler (/usr/bin/../libexec/gcc/darwin/ppc/as or /usr/bin/../local/libexec/gcc/darwin/ppc/as) for architecture ppc not installed
    Installed assemblers are:
    /usr/bin/../libexec/gcc/darwin/x86_64/as for architecture x86_64
    /usr/bin/../libexec/gcc/darwin/i386/as for architecture i386
    src/lxml/lxml.etree.c:161594: fatal error: error writing to -: Broken pipe
    compilation terminated.
    lipo: can't open input file: /var/tmp//ccYr9GpX.out (No such file or directory)
    error: command 'gcc-4.2' failed with exit status 1
    Complete output from command /usr/bin/python -c "import setuptools;__file__='/Users/brianly/dev/github/pyconscrape/build/lxml/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --single-version-externally-managed --record /tmp/pip-axeEA7-record/install-record.txt:
    Building lxml version 2.3.

Building without Cython.

Using build configuration of libxslt 1.1.24

running install

running build

running build_py

creating build

creating build/lib.macosx-10.6-universal-2.6

creating build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/__init__.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/_elementpath.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/builder.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/cssselect.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/doctestcompare.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/ElementInclude.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/pyclasslookup.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/sax.py -> build/lib.macosx-10.6-universal-2.6/lxml

copying src/lxml/usedoctest.py -> build/lib.macosx-10.6-universal-2.6/lxml

creating build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/__init__.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/_dictmixin.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/_diffcommand.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/_html5builder.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/_setmixin.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/builder.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/clean.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/defs.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/diff.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/ElementSoup.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/formfill.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/html5parser.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/soupparser.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

copying src/lxml/html/usedoctest.py -> build/lib.macosx-10.6-universal-2.6/lxml/html

creating build/lib.macosx-10.6-universal-2.6/lxml/isoschematron

copying src/lxml/isoschematron/__init__.py -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron

creating build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources

creating build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/rng

copying src/lxml/isoschematron/resources/rng/iso-schematron.rng -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/rng

creating build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl

copying src/lxml/isoschematron/resources/xsl/RNG2Schtrn.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl

copying src/lxml/isoschematron/resources/xsl/XSD2Schtrn.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl

creating build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_abstract_expand.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_dsdl_include.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_message.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_skeleton_for_xslt1.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_svrl_for_xslt1.xsl -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/readme.txt -> build/lib.macosx-10.6-universal-2.6/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

running build_ext

building 'lxml.etree' extension

creating build/temp.macosx-10.6-universal-2.6

creating build/temp.macosx-10.6-universal-2.6/src

creating build/temp.macosx-10.6-universal-2.6/src/lxml

gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch ppc -arch x86_64 -pipe -I/usr/include/libxml2 -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c src/lxml/lxml.etree.c -o build/temp.macosx-10.6-universal-2.6/src/lxml/lxml.etree.o -w -flat_namespace

/usr/libexec/gcc/powerpc-apple-darwin10/4.2.1/as: assembler (/usr/bin/../libexec/gcc/darwin/ppc/as or /usr/bin/../local/libexec/gcc/darwin/ppc/as) for architecture ppc not installed

Installed assemblers are:

/usr/bin/../libexec/gcc/darwin/x86_64/as for architecture x86_64

/usr/bin/../libexec/gcc/darwin/i386/as for architecture i386

src/lxml/lxml.etree.c:161594: fatal error: error writing to -: Broken pipe

compilation terminated.

lipo: can't open input file: /var/tmp//ccYr9GpX.out (No such file or directory)

error: command 'gcc-4.2' failed with exit status 1

----------------------------------------
  Rolling back uninstall of lxml
Exception:
Traceback (most recent call last):
  File "/Library/Python/2.6/site-packages/pip-1.0.1-py2.6.egg/pip/basecommand.py", line 126, in main
    self.run(options, args)
  File "/Library/Python/2.6/site-packages/pip-1.0.1-py2.6.egg/pip/commands/install.py", line 228, in run
    requirement_set.install(install_options, global_options)
  File "/Library/Python/2.6/site-packages/pip-1.0.1-py2.6.egg/pip/req.py", line 1104, in install
    requirement.rollback_uninstall()
  File "/Library/Python/2.6/site-packages/pip-1.0.1-py2.6.egg/pip/req.py", line 487, in rollback_uninstall
    self.uninstalled.rollback()
  File "/Library/Python/2.6/site-packages/pip-1.0.1-py2.6.egg/pip/req.py", line 1417, in rollback
    pth.rollback()
AttributeError: 'str' object has no attribute 'rollback'

Storing complete log in /Users/brianly/.pip/pip.log

Based on an example provided with the Twitter library for Python I cobbled together the following script to add my latest tweets to this site. It’s called from a cron job that I run on an occasional basis. My script linkifies hashtags and @username tokens in tweets so that you can see search results or user information.

Why did I not use one of the WordPress widgets? Well writing scripts like this is fun, and some widgets don’t seem to play too well with my Thesis theme. One thing to note is that getting the shell script setup under some cron configurations can take a while if you aren’t using it on a regular basis. It’s operation is also different between Ubuntu Server and Joyent’s Accelerator platform.

Up next: a similar script to process my latest bookmarks on Delicious.com.

Main script (tweets.py)

#!/usr/bin/python

import codecs, re, getopt, sys, twitter

TEMPLATE = """
<li>
  <span class="twitter-text">%s</span>
  <span class="twitter-relative-created-at"><a href="http://twitter.com/%s/statuses/%s">Posted %s</a></span>
</li>
"""

def Usage():
  print 'Usage: %s [options] twitterid' % __file__
  print
  print '  This script fetches a users latest twitter update and stores'
  print '  the result in a file as an XHTML fragment'
  print
  print '  Options:'
  print '    --help -h : print this help'
  print '    --output : the output file [default: stdout]'

def FetchTwitter(user, output):
  assert user
  statuses = twitter.Api().GetUserTimeline(user=user, count=7)

  xhtml = []
  for status in statuses:
  	  status.text = Linkify(status.text)
  	  xhtml.append(TEMPLATE % (status.text, status.user.screen_name, status.id, status.relative_created_at))

  if output:
    Save(''.join(xhtml), output)
  else:
    print ''.join(xhtml)

def Linkify(tweet):
    tweet = re.sub(r'(\A|\s)@(\w+)', r'\1@\2', tweet)
    return re.sub(r'(\A|\s)#(\w+)', r'\1#\2', tweet)

def Save(xhtml, output):
  out = codecs.open(output, mode='w', encoding='utf-8',
                    errors='xmlcharrefreplace')
  out.write(xhtml)
  out.close()

def main():
  try:
    opts, args = getopt.gnu_getopt(sys.argv[1:], 'ho', ['help', 'output='])
  except getopt.GetoptError:
    Usage()
    sys.exit(2)
  try:
    user = args[0]
  except:
    Usage()
    sys.exit(2)
  output = None
  for o, a in opts:
    if o in ("-h", "--help"):
      Usage()
      sys.exit(2)
    if o in ("-o", "--output"):
      output = a
  FetchTwitter(user, output)

if __name__ == "__main__":
  main()

Shell script executed as cron job (tweets.sh)

/usr/bin/python /path/to/tweets.py brianly --output /path/to/output/twittertimeline.htm