Pass arbitrary data to pre/body/post

[rreusser]

It's possible to pass a scalar to the body function, but is there any way of passing arbitrary data to the functions? (arg type=object?) I've encountered a couple cases where this would be convenient and, I believe, valid:

• Passing a function to cwise. Think of an image processing function. Unless body implements the function or the function is defined in the containing scope (which isn't always possible if you don't know the function ahead of time, right?), it's not immediately clear how to pass this.
• More questionable uses. I'm currently trying to write a axis-wise function that computes the mean across a number of axes. This can be accomplished with transpose + blockIndices + map-reduce, but it's not clear how to pass the data in/out.

Long story short, here are the two possibilities:

• add an object type for passing arbitrary stuff that's useful
• this isn't really what cwise is for and would defeat the purpose of the useful optimizations it provides

[mikolalysenko]

You can pass objects and functions into the scalar type. The name scalar was chosen because it wasn't an array, so I can understand the confusion. Take a look at ndarray-warp:

https://github.com/scijs/ndarray-warp

[rreusser]

Ah, great. I can submit a PR with this clarification. Thought this might be the case but figured it was worth clarifying whether it was more than an accidental if so.

[rreusser]

cc: @thibauts since it seemed like you might have been working with a similar use-case…

[thibauts]

I had exactly the same question. Might be worthwhile to put the information in the relevant README section so people don't miss it, or alias scalar with something like object that's generic enough for people to feel confident passing functions or arbitrary stuff.

Edit: well, looks like that's exactly what you suggested :)