perf: @pureFunctions decorator

[giogonzo]

requirements:
use @pure (and potentially any other pure-render tool) correctly when props involve .binded and/or partiallly applied functions
i.e: avoid unnecessary re-renderings
see e.g. this for reference: https://discuss.reactjs.org/t/using-function-bind-and-purerendermixin/655

spec proposal:
@pureFunctions decorator, to be used on top of @pure
should let you pass to @pureFunctions-decorated components functions as:

onClick={[myFn, myArg1, myArg2]}

instead of

onClick={myFn.bind(this, myArg1, myArg2)}

and handle properly the reference for the underlying @pure component: reuse cached fn references when fn and args are unchanged

This gives big perf improvements e.g. on LOL/SamplesList for cellRenderer and SampleCard.onClick props

@FrancescoCioria @francescogior thoughts about the syntax?

[FrancescoCioria]

Your solution looks definitely easy to use but not very easy to read and may be hard to debug (is it? I wouldn't know how to improve it actually...). Other possible solutions could be:

• importing and using a utility function as we do for valueLink (it may be more readable, but it would work the same way I think)

onClick={revengeBind(myFn, myArg1, myArg2)}

• passing prop with a special suffix and then removing it to let components use props as usual (black magic?)

bindOnClick={[myFn, arg1, arg2]}

[giogonzo]

onClick={revengeBind(myFn, myArg1, myArg2)}

👍 for something like this. Costs: adds an import on "user" component. Pros: makes it explicit we intend to pass a PureFunction prop

passing prop with a special suffix and then removing it to let components use props as usual

Seems too much, especially considering the above "tagging" mechanism we should be safe enough

[giogonzo]

Added pureFunctionProp, see here for examples: https://github.com/buildo/labonline/commit/9a2257002b4ce4ca0966ba2245d959961d47113a

[giogonzo]

naming is misleading probably, but at least it is clear that it builds on top of a pure render implementation. Merge as it is for now