You will need to load the user object from the DB upon every request. The strongest reason for that requirement is that Flask-Login will check the authentication token every time to ensure its continuing validity. The calculation of this token may require parameters stored on the user object. For example, suppose a user has two … Read more
I searched “python parse html” and this was the first result: https://docs.python.org/2/library/htmlparser.html This code is taken from the python docs from HTMLParser import HTMLParser # create a subclass and override the handler methods class MyHTMLParser(HTMLParser): def handle_starttag(self, tag, attrs): print “Encountered a start tag:”, tag def handle_endtag(self, tag): print “Encountered an end tag :”, tag … Read more
Use: gw_func_dict = dict((chr(2**i), func) for i, func in enumerate(gwfuncs[:8])) That’s the dict() function with a generator expression producing (key, value) pairs. Or, to put it generically, a dict comprehension of the form: {key_expr: value_expr for targets in iterable <additional loops or if expressions>} can always be made compatible with Python < 2.7 by using: … Read more
I’m putting the finishing touches on an approximately 5000 line, deduplicating backup program (http://stromberg.dnsalias.org/~strombrg/backshift/) that runs on CPython 2.[567], CPython 3.[0123] (3.3 is still alpha 0), Pypy 1.7 and Jython trunk. I also tried IronPython, but it was a pretty different thing – it had no standard library, so no backshift love. Oh, and it … Read more
Python 2 uses the naive factorial algorithm: 1121 for (i=1 ; i<=x ; i++) { 1122 iobj = (PyObject *)PyInt_FromLong(i); 1123 if (iobj == NULL) 1124 goto error; 1125 newresult = PyNumber_Multiply(result, iobj); 1126 Py_DECREF(iobj); 1127 if (newresult == NULL) 1128 goto error; 1129 Py_DECREF(result); 1130 result = newresult; 1131 } Python 3 uses the … Read more
Here’s a list of things I can think of that make this dangerous, in rough order from worst to least bad: It’s likely to be confusing to someone reading or debugging your code. You won’t have gotten the right __init__ method, so you probably won’t have all of the instance variables initialized properly (or even … Read more
Try this: [x for x in t if x not in s] You can nest any for if statements in list comprehensions. Try this identation, to get really long chains of conditionals, with a clearer intuition about what the code is doing. my_list = [(x,a) for x in t if x not in s if … Read more
__str__() is the old method — it returns bytes. __unicode__() is the new, preferred method — it returns characters. The names are a bit confusing, but in 2.x we’re stuck with them for compatibility reasons. Generally, you should put all your string formatting in __unicode__(), and create a stub __str__() method: def __str__(self): return unicode(self).encode(‘utf-8’) … Read more
Python has these two (among others) builtin objects. They are just objects; in the beginning, they don’t have any names yet, but to know what we refer to, let’s call them 0x600D and 0xBAD. Before starting to execute a Python (2.x) script, the name True gets bound to the object 0x600D, and the name False … Read more
The original poster asked for code which demonstrates that the switch is harmful—except that it “hides” bugs unrelated to the switch. Updates [2020-11-01]: pip install setdefaultencoding Eradicates the need to reload(sys) (from Thomas Grainger). [2019]: Personal experience with python3: No unicode en/decoding problems. Reasons: Got used to writing .encode(‘utf-8’) .decode(‘utf-8’) a (felt) 100 times a … Read more