When we use css-sprites it's important to make browser cache them for longest period possible. On other hand, we need to refresh them when they are updated. This is especially visible when all icons are stored in single sprite. When it's outdated - entire site becomes ugly.
To solve this task I've implemented this small script that adds file's hash to url:
background-image: url(images/icons.png);
background-image: url(images/icons.png?a3844c660);#!/usr/bin/python
import os.path
import re
import hashlib
def file_hash(filename, block_size=2**20):
md5 = hashlib.md5()
with open(filename, 'rb') as f:
for data in iter(lambda: f.read(block_size), ''):
md5.update(data)
return md5.hexdigest()
def find_replace(match, basedir):
match = match.replace("'", '')
if '?' in match or '#' in match or match.startswith('http://'):
print 'skipping: ', match
return None
filename = os.path.join(basedir, match)
return '%s?%s' % (match, file_hash(filename)[:10])
def insert_hash(filename, debug=False):
basedir = os.path.dirname(filename)
css = open(filename).read()
matches = re.findall(r"url\((.*?)\)", css)
replacements = dict([
(match, find_replace(match, basedir))
for match in matches
])
if debug:
for key, value in replacements.iteritems():
print key, ' => ', value
else:
for match, repl in replacements.iteritems():
if repl:
css = css.replace(match, repl)
out = open(filename, 'w')
out.write(css)
out.close()
if __name__ == '__main__':
from optparse import OptionParser
usage = 'usage: %prog filename.css'
parser = OptionParser(usage=usage)
parser.add_option("", "--debug", action="store_true", dest="debug", default=False,
help="When set, just output list of substitutions.")
(options, args) = parser.parse_args()
if len(args) < 1:
print 'You must provide file name.'
insert_hash(os.path.realpath(args[0]), options.debug)Update
This is pretty old article. Now it's better to use something integrated to your build process - grunt, webassets, etc.
Subscribe for the news and updates
This article explores how Stoic principles can be applied in the workplace to navigate stress, improve self-control, and focus on what truly matters, with practical examples from the author’s experience in software development.
This article offers key insights into the ISTQB certification and shares a proven preparation strategy to help candidates succeed.
We’ll tell you how to create a video timelapse from a sequence of snapshots and provide customers with video playlists optimized for browser playback.
One of the key requirements for modern UI is being performant. No matter how beautiful your app looks and what killer features it offers, it will frustrate your users if it clangs.
It appears that not everyone knows that in python you can create classes dynamically without metaclasses. I'll show an example of how to do it.So we've learned how to use custom QuerySet to chain requests:Article.objects.old().public()Now we need to make it work for related objects:user.articles.old().public()This is done using use_for_related_fields, but it needs a little trick.
Usually users' profiles are stored in single model. When there are multiple user types, separation is made by some field like user_type.Situation is a little more complicated when different data is needed for each user type.In this article I'll describe how I solve this task.