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What is the purpose of Flask's context stacks?
I've been using the request/application context for some time without fully understanding how it works or why it was designed the way it was. What is the purpose of the "stack" when it comes to the request or application context? Are these two separate stacks, or are they both part of one stack? Is ...
How do I initialize the base (super) class?
... invoke their base class through super(), e.g.
class X(object):
def __init__(self, x):
pass
def doit(self, bar):
pass
class Y(X):
def __init__(self):
super(Y, self).__init__(123)
def doit(self, foo):
return super(Y, self).doit(foo)
Because python knows about old- and ne...
How to make a class JSON serializable
...out the expected output? For example, will this do?
>>> f = FileItem("/foo/bar")
>>> magic(f)
'{"fname": "/foo/bar"}'
In that case you can merely call json.dumps(f.__dict__).
If you want more customized output then you will have to subclass JSONEncoder and implement your own ...
How does the @property decorator work in Python?
.... What confuses me is that property can also be used as a decorator, but it only takes arguments when used as a built-in function and not when used as a decorator.
...
Is there a replacement for unistd.h for Windows (Visual C)?
I'm porting a relatively simple console program written for Unix to the Windows platform ( Visual C++ 8.0 ). All the source files include "unistd.h", which doesn't exist. Removing it, I get complaints about misssing prototypes for 'srandom', 'random', and 'getopt'.
I know I can replace the random f...
Proper way to declare custom exceptions in modern Python?
...sed the question, but why not:
class MyException(Exception):
pass
Edit: to override something (or pass extra args), do this:
class ValidationError(Exception):
def __init__(self, message, errors):
# Call the base class constructor with the parameters it needs
super(Valida...
编译失败！ Error: Your build failed due to an error in the AAPT stage,...
编译apk报错如下：
经过日志分析如下：
Tag <activity> attribute name has invalid character
[java] /tmp/1685410160630_0.39828964915976717-0/youngandroidproject/../build/AndroidManifest.xml:5: Tag <activity> attribute name has invalid character '�'.
&n...
What is the list of supported languages/locales on Android?
...[Amharic (Ethiopia)]
ar_ [Arabic]
ar_001 [Arabic (World)]
ar_AE [Arabic (United Arab Emirates)]
ar_BH [Arabic (Bahrain)]
ar_DJ [Arabic (Djibouti)]
ar_DZ [Arabic (Algeria)]
ar_EG [Arabic (Egypt)]
ar_EH [Arabic (Western Sahara)]
ar_ER [Arabic (Eritrea)]
ar_IL [Arabic (Israel)]
ar_IQ [Arabic (Iraq)]
ar...
Getting the class name of an instance?
...he name of the class, which I think is what you want.
>>> import itertools
>>> x = itertools.count(0)
>>> type(x).__name__
'count'
If you're still using Python 2, note that the above method works with new-style classes only (in Python 3+ all classes are "new-style" clas...
In which case do you use the JPA @JoinTable annotation?
...
EDIT 2017-04-29: As pointed to by some of the commenters, the JoinTable example does not need the mappedBy annotation attribute. In fact, recent versions of Hibernate refuse to start up by printing the following error:
org.hib...