Why package is not generated in one Python module?

[mikir]

For Python users, it would be much more convenient if all package symbols (constants, structures, etc...) will be generated in one module.

Currently, this is not possible because of the following problems:

1. Symbol dependencies

   Zserio compiler allows dependencies which are defined after reference. Example:

   const uint32 A = B;
   const uint32 B = 10;
   
   struct Main
   {
       Item item;
   };
   
   struct Item
   {
       uint32 value;
   };
   

   Python does not allow such dependencies, each referenced symbol must be defined before it is used.

2. Cyclic imports

   Zserio allows cyclic imports. Python does not support cyclic dependencies at all. However, Zserio does not allows indirection recursion. Thus when e.g. StructureA needs field of StructureB, it can never happen that also StructureB will need StructureA as a field. Putting these two things together, the approach with seperate module for each Zserio entity works even if target language does not support cyclic dependecies at all.

See Also:

• Discussion Emit one Python module per Zserio package #437