Overload ifthen

General Usage
1

In julia 0.7, I had overloaded

    Base.ifelse(cond::𝕓,a::βˆ‚π•£{N},b::𝕣) where{N} = cond ? a        : βˆ‚π•£{N}(b)
    Base.ifelse(cond::𝕓,a::𝕣,b::βˆ‚π•£{N}) where{N} = cond ? βˆ‚π•£{N}(a) : b

essentialy so that

x=cond ? a : b

would promote the output, to get a typestable operation when a and b have different types.

Porting to 1.0, I get LoadError: cannot add methods to a builtin function. In the context of automatic differentiation, this allows me to transparently write typestable code when some variables may be β€œspiced up” as dual/autodiff numbers.

I could write a function ifthen, with the obvious drawback of forcing the evaluation of both a and b. I could write a macro, but then I can no longer write a function ignoring automatic differentiation ('xept for dispatching…) and then use it efficiently with automatic differentiation.

Any ideas?

2

The old ifelse function already evaluated all of its arguments (it has to, since it’s a function), so I don’t think there’s actually any practical downside to just defining your own ifthen.

1 Like
3

He he, my mistake. Rereading my code after a long while, I though it was overloading cond ? a : b !!!
Then it’s easy to fix.

Thank you!