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How to know if an object has an attribute in Python
...n is that, if the property is likely to be there most of the time, simply call it and either let the exception propagate, or trap it with a try/except block. This will likely be faster than hasattr. If the property is likely to not be there most of the time, or you're not sure, using hasattr will pr...
Loop backwards using indices in Python?
... This is better than the accepted answer since it doesn't actually allocate all the numbers in memory (in Python 3 the accepted answer wouldn't either), plus it's more obvious what is happening.
– Blixt
Mar 23 '12 at 13:52
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Unique BooleanField value in Django?
... save method of the model and if you've set the boolean to True, make sure all others are set to False.
from django.db import transaction
class Character(models.Model):
name = models.CharField(max_length=255)
is_the_chosen_one = models.BooleanField()
def save(self, *args, **kwargs):
...
Find an item in List by LINQ?
Here I have a simple example to find an item in a list of strings. Normally I use for loop or anonymous delegate to do it like this:
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How do I create a multiline Python string with inline variables?
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This isn't really the same because the OP wants named parameters, not positional ones.
– Ismail Badawi
Apr 11 '12 at 19:33
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Exif manipulation library for python [closed]
...mation from Jpeg and Tiff files which include it. This information is typically included in images created using digital imaging devices such as digital cameras, digital film scanners, etc.
However, it looks like pyexif hasn't been updated in quite while. They recommend if theirs isn't doing the ...
The model used to open the store is incompatible with the one used to create the store
...el select your new version of data model for current data model
THAT'S NOT ALL ) You should perform so called "light migration".
Go to your AppDelegate and find where the persistentStoreCoordinator is being created
Find this line if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteS...
Aren't Python strings immutable? Then why does a + “ ” + b work?
...the variable a to point at a new string "Dog eats treats". You didn't actually mutate the string "Dog". Strings are immutable, variables can point at whatever they want.
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Execution of Python code with -m option or not
...st python -m foo.bar.baz
foo.bar
__main__
As a result, Python has to actually care about packages when using the -m switch. A normal script can never be a package, so __package__ is set to None.
But run a package or module inside a package with -m and now there is at least the possibility of a pac...
What's the difference between a Python “property” and “attribute”?
I am generally confused about the difference between a "property" and an "attribute", and can't find a great resource to concisely detail the differences.
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