What is an appropriate design for passing keyword arguments to a builder that contains component sub-builders which each use a distinct portion of the parameter set? Is it better to pass in a single keyword parameter set which is then parsed by each sub-builder? Or is it better to explicity specify which parameter sets belong to which sub-builders when calling the parent builder?
I know "better" can be subjective in these kinds of situations but I am wondering if there is some collective wisdom I can draw from, here. Also, note that in the details below I'm using a feature specific to the Python language but any thoughts on how other languages manage this situation is appreciated.
Details - I am using a builder design pattern where BuilderA
contains sub-builders BuilderB()
and BuilderC
. My current thought on the design was to pass the same set of keyword arguments to each sub-builder:
class BuilderA():
def __init__(self):
self.builder_b = BuilderB()
self.builder_c = BuilderC()
def build(self, **build_parameters):
artifact_b = self.builder_b.build(**build_parameters)
artifact_c = self.builder_c.build(**build_parameters)
# ... do something to create BuilderA's artifact ...
Each sub-builder has distinct keyword parameters:
class BuilderB():
def build(self, param_1=None, param_2=None, **ignored_kwds):
# ...
class BuilderC():
def build(self, param_3=None, param_4=None, **ignored_kwds):
# ...
Alternatively, BuilderA
's API could look like this:
class BuilderA():
def build(self, builder_b_parameters={}, builder_c_parameters={}):
artifact_b = self.builder_b.build(**builder_b_parameters)
artifact_c = self.builder_c.build(**builder_c_parameters)
# ... do something to create BuilderA's artifact ...
Is one of these designs, generally, more acceptable than the other? Or is there another option I haven't considered?
Thoughts - The first design is cleaner but prevents BuilderB
and BuilderC
from sharing keyword names. Plus, it requires that each of their builders includes **ignored_kwds
in its build method declaration. The danger of this approach is that if the user misspells a keyword argument then there can be unexpected behavior without error. On the other hand, the second design makes the interface to BuilderA
more cumbersome but resolves the aforementioned issues.
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