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Does Python optimize tail recursion?
...tracebacks:
Tail Recursion Elimination (2009-04-22)
Final Words on Tail Calls (2009-04-27)
You can manually eliminate the recursion with a transformation like this:
>>> def trisum(n, csum):
... while True: # Change recursion to a while loop
... if n == 0:...
What is the best regular expression to check if a string is a valid URL?
...
I wrote my URL (actually IRI, internationalized) pattern to comply with RFC 3987 (http://www.faqs.org/rfcs/rfc3987.html). These are in PCRE syntax.
For absolute IRIs (internationalized):
/^[a-z](?:[-a-z0-9\+\.])*:(?:\/\/(?:(?:%[0-9a-f][0-9a-f]...
Python Unicode Encode Error
...80\x80abcd\xde\xb4'
>>> u.encode('ascii')
Traceback (most recent call last):
File "<stdin>", line 1, in ?
UnicodeEncodeError: 'ascii' codec can't encode character '\ua000' in position 0: ordinal not in range(128)
>>> u.encode('ascii', 'ignore')
'abcd'
>>> u.encode(...
What is a regular expression which will match a valid domain name without a subdomain?
...
This should match all cases I think: ^([a-z0-9])(([a-z0-9-]{1,61})?[a-z0-9]{1})?(\.[a-z0-9](([a-z0-9-]{1,61})?[a-z0-9]{1})?)?(\.[a-zA-Z]{2,4})+$
– transilvlad
May 16 '13 at 16:38
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Backbone.js: get current route
... hashchange events or pushState, match the appropriate route, and trigger callbacks. You shouldn't ever have to create one of these yourself — you should use the reference to Backbone.history that will be created for you automatically if you make use of Routers with routes.
[...]"
If you need the...
Create a pointer to two-dimensional array
...d T[10] are different types.
The following alternative doesn't work at all, because the element type of the array, when you view it as a one-dimensional array, is not uint8_t, but uint8_t[20]
uint8_t *matrix_ptr = l_matrix; // fail
The following is a good alternative
uint8_t (*matrix_ptr)[...
Circular list iterator in Python
...
Output:
a b c a b c ...
(Loops forever, obviously)
In order to manually advance the iterator and pull values from it one by one, simply call next(pool):
>>> next(pool)
'a'
>>> next(pool)
'b'
share...
No generic implementation of OrderedDictionary?
...s methods for sorting the way that List<T> does since this is essentially a hybrid IList and IDictionary. I've included my implementation here for posterity.
Here's the interface. Notice that it includes System.Collections.Specialized.IOrderedDictionary, which is the non-generic version of t...
Manually raising (throwing) an exception in Python
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How do I manually throw/raise an exception in Python?
Use the most specific Exception constructor that semantically fits your issue.
Be specific in your message, e.g.:
raise ValueError('A very specific bad thing happened.')
Don't ...
What does the Ellipsis object do?
While idly surfing the namespace I noticed an odd looking object called Ellipsis , it does not seem to be or do anything special, but it's a globally available builtin.
...