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How to print instances of a class using print()?
...
>>> class Test:
... def __repr__(self):
... return "Test()"
... def __str__(self):
... return "member of Test"
...
>>> t = Test()
>>> t
Test()
>>> print(t)
member of Test
The __str__ method is what h...
Difference between partition key, composite key and clustering key in Cassandra?
...tition key columns, then you can add optionally each clustering key in the order they're set.
so the valid queries are (excluding secondary indexes)
col1 and col2
col1 and col2 and col10
col1 and col2 and col10 and col 4
Invalid:
col1 and col2 and col4
anything that does not contain both col1...
What is the fastest way to get the value of π?
...ically, I'm using ways that don't involve using #define constants like M_PI , or hard-coding the number in.
22 Answers
...
NHibernate ISession Flush: Where and when to use it, and why?
...it()
from ISession.Flush()
The SQL statements are issued in the following order
all entity insertions, in the same order the corresponding objects were saved using ISession.Save()
all entity updates
all collection deletions
all collection element deletions, updates and insertions
all collection in...
Python __str__ and lists
...
Calling string on a python list calls the __repr__ method on each element inside. For some items, __str__ and __repr__ are the same. If you want that behavior, do:
def __str__(self):
...
def __repr__(self):
return self.__str__()
...
Is multiplication and division using shift operators in C actually faster?
...with the core i7:
(from http://software.intel.com/en-us/forums/showthread.php?t=61481)
The latency is 1 cycle for an integer addition and 3 cycles for an integer multiplication. You can find the latencies and thoughput in Appendix C of the "Intel® 64 and IA-32 Architectures Optimization Refere...
Is there a Python caching library?
...
From Python 3.2 you can use the decorator @lru_cache from the functools library.
It's a Last Recently Used cache, so there is no expiration time for the items in it, but as a fast hack it's very useful.
from functools import lru_cache
@lru_cache(maxsize=256)
def f(x):
...
Composite Key with EF 4.1 Code First
...uld work - composite key defined with annotations requires explicit column order:
public class ActivityType
{
[Key, Column(Order = 0)]
public int ActivityID { get; set; }
[Key, Column(Order = 1)]
[Required(ErrorMessage = "A ActivityName is required")]
[StringLength(50, ErrorMes...
How to retrieve a module's path?
...
import a_module
print(a_module.__file__)
Will actually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do:
import os
path = os.path.abspath(a_module.__file__)
You can also try:
path ...
Purpose of Python's __repr__
...
__repr__ should return a printable representation of the object, most likely one of the ways possible to create this object. See official documentation here. __repr__ is more for developers while __str__ is for end users.
A ...