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How does deriving work in Haskell?
... Haskell Wiki:
In this example we use the following Haskell code
$(gen_render ''Body)
to produce the following instance:
instance TH_Render Body where
render (NormalB exp) = build 'normalB exp
render (GuardedB guards) = build 'guardedB guards
The function gen_render above is d...
List all indexes on ElasticSearch server?
...ise list of all indices in your cluster, call
curl http://localhost:9200/_aliases
this will give you a list of indices and their aliases.
If you want it pretty-printed, add pretty=true:
curl http://localhost:9200/_aliases?pretty=true
The result will look something like this, if your indices ...
Reference — What does this symbol mean in PHP?
...
_ Alias for gettext()
The underscore character '_' as in _() is an alias to the gettext() function.
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Instance attribute attribute_name defined outside __init__
.... We expect to find all the attributes an instance may have by reading its __init__ method.
You may still want to split initialization into other methods though. In such case, you can simply assign attributes to None (with a bit of documentation) in the __init__ then call the sub-initialization met...
What does $_ mean in PowerShell?
...ich is called $PSItem in Powershell 3 and newer.
1,2,3 | %{ write-host $_ }
or
1,2,3 | %{ write-host $PSItem }
For example in the above code the %{} block is called for every value in the array. The $_ or $PSItem variable will contain the current value.
...
How can I recover the return value of a function passed to multiprocessing.Process?
... For example like this:
import multiprocessing
def worker(procnum, return_dict):
'''worker function'''
print str(procnum) + ' represent!'
return_dict[procnum] = procnum
if __name__ == '__main__':
manager = multiprocessing.Manager()
return_dict = manager.dict()
jobs = []
...
Length of generator output [duplicate]
...
The easiest way is probably just sum(1 for _ in gen) where gen is your generator.
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Accessing Object Memory Address
When you call the object.__repr__() method in Python you get something like this back:
9 Answers
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Can a dictionary be passed to django models on create?
...our model is called MyModel:
# create instance of model
m = MyModel(**data_dict)
# don't forget to save to database!
m.save()
As for your second question, the dictionary has to be the final argument. Again, extra and extra2 should be fields in the model.
m2 =MyModel(extra='hello', extra2='world'...
How do I flag a method as deprecated in Objective-C 2.0?
...x is provided to mark methods as deprecated:
@interface SomeClass
-method __attribute__((deprecated));
@end
or:
#include <AvailabilityMacros.h>
@interface SomeClass
-method DEPRECATED_ATTRIBUTE; // or some other deployment-target-specific macro
@end
...