I have object initializer in my code, that initializes every field of my object explicitly. But in my case, most of the parameters have sensible defaults and I want to use them.
In Python I usually use combination of keyword arguments or defaults and my __init__ method contains some validation logic so I can use zero configuration principle in object initialization. For example:
class Foo:
"""This class designed to show zero configuration
principle in action"""
def __init__(self, mandatory, optional=None, **kwargs):
self.__field1 = mandatory
self.__field2 = optional or make_default2()
if 'bar' in kwargs:
self.__field3 = kwargs['bar']
else:
self.__field3 = make_default3()
f = Foo('mondatory', bar=Bar())
There is no parameters with default values in Go nor keyword parameters or function overloads. Because of that - it is difficult to write flexible initialization code (I don't care much about performance in such code usually). I want to find most idiomatic way to write such code in Go. Maybe some combination of runtime type reflection and maps will do the job, what do you think?
Because newly-allocated memory in Go is always zeroed, the idiomatic way is to make explicit use of this fact by:
Take a look at the following section of Effective Go: http://golang.org/doc/effective_go.html#data
For extremely complex cases, a configuration struct (option 3 at http://joneisen.tumblr.com/post/53695478114/golang-and-default-values) is also sometimes used, with a NewConfigStruct() that initializes a configuration instance with defaults. The user generates a default instance, sets the fields they want, then passes it to the New function for the actual struct they are creating.