Cannonical way to do circular dependency in Nim -


suppose have 2 modules: 1 defines object , 1 defines objectfactory. object needs have access objectfactory use of functions, , objectfactory needs access object able instantiate objects.

what cannonical way solve in nim if object implemented in module , objectfactory implemented in module?

i assuming issue here mutually recursive types, i.e. declarations of 2 or more types refer 1 another. methods or procedures refer 1 handled fine mutually recursive imports, though 1 has careful module initialization in case.

as in other languages require mutually recursive types within same module/compilation unit, there 2 principal answers.

one solution have 2 types within same module imported both module declares object type , module declares factory type (both types still need part of same type clause). e.g., create separate file, called factory_types.nim, , put both types in it:

type   objectfactory = ref object     lastvalue: object     x: proc(): object    object = ref object     factory: objectfactory

this module imported both module implementing object , module implementing factory.

the other solution, can keep each type in module, parametric polymorphism, type parameter used forward declaration. e.g., do:

type   objectfactory[targettype] = ref object     lastvalue: targettype     generator: proc(): targettype

and elsewhere:

type   object = ref object     factory: objectfactory[object]

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