Uniformize variable declaration : allow inputs to be declared as a formula without a function

[fpagnoux]

As discussed with @eraviart last Friday, declaring formulas and input in different ways has a few drawbacks :

• More complexity for the developer, who has to know 2 ways of declaring a variable that look like each other with a slightly different syntax.
• Possible mistakes (comas are needed in one syntax, not the other)
• When looking for a variable declaration with a global text research, inputs are hard to find.

It would be nice if we could have only one syntax. A possible implementation (started here) is to just allow SimpleFormulaColumn to not have a function.

Before :

reference_input_variable(
    name = "ass_precondition_remplie",
    column = BoolCol,
    entity_class = Individus,
    label = u"Eligible à l'ASS",
    )

@reference_formula
class ass(SimpleFormulaColumn):
    column = FloatCol
    label = u"Montant de l'ASS pour une famille"
    entity_class = Familles

    def function(self, simulation, period):
         return period, x

After :

@reference_formula
class ass_precondition_remplie(SimpleFormulaColumn):
    column = BoolCol
    entity_class = Individus
    label = u"Eligible à l'ASS"

@reference_formula
class ass(SimpleFormulaColumn):
    column = FloatCol
    label = u"Montant de l'ASS pour une famille"
    entity_class = Familles

    def function(self, simulation, period):
         return period, x

[fpagnoux]

I'm not sure entirely sure this is ready to merge right now, but tests seem to be ok on my computer. Maybe the core team to have a look to make sure everything is not broken :)

[benjello]

Why not but one should rename formula to variable somehow. A formula without a function is a bit awkward.

[fpagnoux]

Good point, thanks !

Something like that ?

@reference_variable
class ass_precondition_remplie(SimpleVariable):
    column = BoolCol
    entity_class = Individus
    label = u"Eligible à l'ASS"

Btw, what does reference mean in reference_formula ?

[benjello]

reference is for "root" tax_benefit_system vs reform IIRC @cbenz @eraviart

[fpagnoux]

Ok, I understand better, thanks :)

[cbenz]

Furthermore I would suggest renaming even @reference_formula to @reference_variable, because a variable can have or not a formula. The formula is the function.

We could even replace the term reference by either vanilla (like @benjello says often), country or tax_benefit_system

[fpagnoux]

@vanilla_variable does not seem very explicit to me. What do you think about @law_variable ?

[benjello]

@reference_variable is good for me

[fpagnoux]

I tend to agree with @cbenz that for contributors who are only using Openfisca to run simulation about the actual law and are not trying potential reforms (e.g. embauche or mes-aides), the term reference doesn't mean much and is pretty unclear.

Ideally, it would be nice to have a term that makes sense both for the distinction reference vs reform, and for use cases without reform.

[benjello]

If we use core_variable it will mess-up with openfisca-core.
Should we use reference_variable or base_variable and have two distinct term for reform and extension ?

[cbenz]

I close this pull request but opened a new issue: #355