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Specifying rails version to use when creating a new application
I have two versions of rails (2.1.0 and 2.2.2) installed in my computer.
7 Answers
7
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How do you serialize a model instance in Django?
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You can easily use a list to wrap the required object and that's all what django serializers need to correctly serialize it, eg.:
from django.core import serializers
# assuming obj is a model instance
serialized_obj = serializers.serialize('json', [ obj, ])
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Static class initializer in PHP
I have an helper class with some static functions. All the functions in the class require a ‘heavy’ initialization function to run once (as if it were a constructor).
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Sort Go map values by keys
...tween runs of the program. In practice, not only is it undefined, it's actually intentionally randomized. This is because it used to be predictable, and the Go language developers didn't want people relying on unspecified behavior, so they intentionally randomized it so that relying on this behavior...
How to write iOS app purely in C
...d in remain the same whether or not
// you are using VA_ARGS. This is actually the basis of the objective-c
// runtime (objc_msgSend), so we are probably fine here, this would be
// the last thing I would expect to break.
extern int UIApplicationMain(int, ...);
// Entry point of the application....
Convert a series of parent-child relationships into a hierarchical tree?
...o '</ul>';
}
}
You'll only save 8 iterations on a dataset as small as this but on bigger sets it could make a difference.
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Calculate difference in keys contained in two Python dictionaries
...s:
diff = set(dictb.keys()) - set(dicta.keys())
Here is a class to find all the possibilities: what was added, what was removed, which key-value pairs are the same, and which key-value pairs are changed.
class DictDiffer(object):
"""
Calculate the difference between two dictionaries as:
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Why does changing 0.1f to 0 slow down performance by 10x?
...ond run the numbers are very close to zero.
Denormalized numbers are generally rare and thus most processors don't try to handle them efficiently.
To demonstrate that this has everything to do with denormalized numbers, if we flush denormals to zero by adding this to the start of the code:
_MM_...
Calling parent class __init__ with multiple inheritance, what's the right way?
...ing super() leads to greater flexibility for subclasses.
In the direct call approach, C.__init__ can call both A.__init__ and B.__init__.
When using super(), the classes need to be designed for cooperative multiple inheritance where C calls super, which invokes A's code which will also call supe...
Preloading images with JavaScript
Is the function I wrote below enough to preload images in most, if not all, browsers commonly used today?
14 Answers
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