query = Query("name == 'Bob' and age > (15 + 1)")
solve(query, dict(name="Alice", age=20)) # => False
solve(query, dict(name="Bob", age=20)) # => True
infer_type(query) # => bool
infer_type(Query("15 + 1")) # => int

class Customer(object):
	"""My awesome Customer business logic class."""
	
	@property
	def name(self):
		#...
	
	@property
	def age(self):
		#...
	
	@property
	def admin(self):
		#...

from efilter.protocols import associative
associative.IAssociative.implement(
	for_type=Customer,  # This is how you access Customer's data.
	implementations={
		# Select is similar to dict().get()
		associative.select: lambda c, key: getattr(c, key, None),
		
		# Resolve is similar, but allowed to use magic to look
		# up more data. For example, selecting 'admin' will
		# return the ID of the admin user, but resolving
		# 'admin' might return the user object representing
		# the admin.
		associative.resolve: lambda c, key: getattr(c, key, None),
		
		# Getkeys is kind of obvious: the keys that can be
		# accessed.
		associative.getkeys: lambda _: ("name", "age", "admin")
	})

query = Query("name == 'Bob'")
solve(query, Customer(name="Bob")) # => True