大约有 46,000 项符合查询结果（耗时：0.0424秒） [XML]
Difference between a theta join, equijoin and natural join
...
A theta join allows for arbitrary comparison relationships (such as ≥).
An equijoin is a theta join using the equality operator.
A natural join is an equijoin on attributes that have the same name in each relationship.
Additionally,...
How to manually create icns files using iconutil?
...following instructions (link):
Use iconutil to Create an icns File Manually
The iconutil command-line tool converts iconset folders to deployment-ready, high-resolution icns files. (You can find complete documentation for this tool by entering man iconutil in Terminal.) Using this tool al...
Why does Python use 'magic methods'?
...lable, an object implements a method, def __len__(self) , and then it is called when you write len(obj) .
7 Answers
...
Difference between String replace() and replaceAll()
What's the difference between java.lang.String 's replace() and replaceAll() methods,
other than later uses regex? For simple substitutions like, replace . with / ,
is there any difference?
...
Dictionary vs Object - which is more efficient and why?
...ots__ = ('i', 'l')
def __init__(self, i):
self.i = i
self.l = []
all = {}
for i in range(1000000):
all[i] = Obj(i)
test_obj.py:
class Obj(object):
def __init__(self, i):
self.i = i
self.l = []
all = {}
for i in range(1000000):
all[i] = Obj(i)
test_dict.py:
all = {}
for i in...
How to get the parents of a Python class?
...
If you want all the ancestors rather than just the immediate ones, use inspect.getmro:
import inspect
print inspect.getmro(cls)
Usefully, this gives you all ancestor classes in the "method resolution order" -- i.e. the order in which ...
How do I get the path of the current executed file in Python?
...ike a newbie question, but it is not. Some common approaches don't work in all cases:
13 Answers
...
Build a Basic Python Iterator
...
Iterator objects in python conform to the iterator protocol, which basically means they provide two methods: __iter__() and __next__().
The __iter__ returns the iterator object and is implicitly called
at the start of loops.
The __next__() method returns the next value and is implicitly cal...
Inverse dictionary lookup in Python
...o guarantee that it returns a single value and it does not need to be lexically first only that it be the first match and that it's behavior is stable (multiple calls on same dict over time should yield same matching element). Unless dictionaries rearrange their unmodified hashes over time as other...
How does Python's super() work with multiple inheritance?
...ave trouble
understanding the super() function (new style classes) especially when it comes to multiple inheritance.
16 A...