I understand decorators on a base level but am confused by @django.display()

Question

Working through the django tutorials and came across the following code:

@admin.display(
    boolean=True,
    ordering='pub_date',
    description='Published recently?',
)

Had no idea what it was so I did some googling and learned what decorators are in Python. I feel comfortable with that topic.

However, in all the videos and docs I went through I didn’t see an example like @admin.display()

Only things like @log or @timer. Pretty much just a simple class or function decorator.

My guess is that @admin.display is a decorator where admin is the class and display is one of many wrapper methods(is that even possible) in that class?

Just confused I guess as to the syntax as I can’t find any examples like it 🙁

Asked By: jarjarbinks99

||

Source

Answer 1

The way to parse this is:

@ is special decorator syntax
admin and its attribute display are both objects
the (boolean=True, ...) means display must be callable, i.e. display.__call__() will be executed

When you see something like:

@log
def my_method():
    return 'blah'

It’s effectively the same as: my_method = log(my_method)

Next, consider:

@configurable_log(config_val)
def my_method():
    return 'blah'

Which is the same as: my_method = configurable_log(config_val)(my_method)

configurable_log is a callable taking config args (i.e. configurable_log(config_val)) which returns another callable, which is passed my_method. In other words, it’s the same as:

configured_log_decor = configurable_log(config_val)
@configured_log_decor  # a "no parens" decorator
def my_method():
    return 'blah'

The last remaining part is just normal attribute access, e.g.:

SomeClass.attr_of_class
some_instance.attr_of_instance
some_module.attr_of_module

Answered By: Kache

I understand decorators on a base level but am confused by @django.display()

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