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Difference between left join and right join in SQL Server [duplicate]
...indeed completely interchangeable. Try however Table2 left join Table1 (or its identical pair, Table1 right join Table2) to see a difference. This query should give you more rows, since Table2 contains a row with an id which is not present in Table1.
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Print all properties of a Python Class [duplicate]
I have a class Animal with several properties like:
6 Answers
6
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Finding what methods a Python object has
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For many objects, you can use this code, replacing 'object' with the object you're interested in:
object_methods = [method_name for method_name in dir(object)
if callable(getattr(object, method_name))]
I discovered it at diveintopython.net (Now archived). Hopefully...
A python class that acts like dict
I want to write a custom class that behaves like dict - so, I am inheriting from dict .
9 Answers
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What is the meaning of single and double underscore before an object name?
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Single Underscore
Names, in a class, with a leading underscore are simply to indicate to other programmers that the attribute or method is intended to be private. However, nothing special is done with the name itself.
To quote PEP-8:
_single_leading_undersc...
What is __main__.py?
What is the __main__.py file for, what sort of code should I put into it, and when should I have one?
5 Answers
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What __init__ and self do on Python?
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In this code:
class A(object):
def __init__(self):
self.x = 'Hello'
def method_a(self, foo):
print self.x + ' ' + foo
... the self variable represents the instance of the object itself. Most object-oriented languages pass this as a hidden p...
What are some (concrete) use-cases for metaclasses?
... Matplotlib. However, on occasion one wants to do interactive plotting. With only a couple functions I found that I was able to increment the figure count, call draw manually, etc, but I needed to do these before and after every plotting call. So to create both an interactive plotting wrapper and...
What is a “callable”?
Now that it's clear what a metaclass is , there is an associated concept that I use all the time without knowing what it really means.
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Immutability of Strings in Java
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str is not an object, it's a reference to an object. "Hello" and "Help!" are two distinct String objects. Thus, str points to a string. You can change what it points to, but not that which it points at.
Take this code, for example:
String s1 = "He...