Comment by hinkley 2 days ago
The way to solve this is to split decisions from execution and that’s a notion I got from our old pal Bertrand Meyer.
if (weShouldDoThis()) {
doThis();
}
One possibility is a file.py that is called by your framework. The interface could be something like
def doth_match(*args):
return True # the predicate
def doeth_thou(*args):
# processing things
return {} # status object for example
There could be multiple files rule1.py, rule2.py, etc that check and do different things.
I think the parent's argument is that wherever in your framework you're calling `doth_match` and then `doeth_thou`, you have a single function that's both deciding and acting. There has to be a function in your program that's responsible for doing both.
A function that asks a question with one function call and calls another based on the answer isn’t doing any work or asking any questions. It’s just glue code. And as long as it stays just glue code, that’s barely any of your code.
Asking for absolutes is something journeymen developers need to grow out of.
The principle of the excluded middle applies to Boolean logic and bits of set theory and belongs basically nowhere else in software development. But it’s a one trick pony that many like to ride into the ground.
This just moves decisions from inside of functions to the call site. At which point, there's more that can go wrong, since you're calling a function much more than it's single definition.
This is not obvious to me. The whole point was to separate the conditionals from the actions.
In your example, it’s not clear if/how much “should we do this” logic is in your function. If none, then great; you’ve implemented a find or lookup function and I agree those can be helpful.
If there’s some logic, eg you have to iterate through a set or query a database to find all the things that meet the criteria for “should do this”, then that’s different than what the original commenter was saying.
maybe: doThis( findAllMatchingThings( determineCriteriaForThingsToDoThisTo()))
would be a good separation of concerns
Functions should decide or act, not both.