# ANN: CBOOCall

**URL:** <https://discourse.julialang.org/t/ann-cboocall/81420>\
**Category:** General Usage\
**Tags:** announcement\
**Created:** [May 21, 2022, 2:38pm UTC](https://discourse.julialang.org/t/ann-cboocall/81420 "2022-05-21T14:38:17Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![jlapeyre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jlapeyre/32/4514_2.png) [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Post date:** [May 21, 2022, 2:38pm UTC](https://discourse.julialang.org/t/ann-cboocall/81420/1 "2022-05-21T14:38:17Z")

</div>

From the README of [CBOOCall.jl](https://github.com/jlapeyre/CBOOCall.jl):

`split(",", "a,b,c")` is not really the right way to do it.  
`split` only works with strings, so it should be a class method.  
We should be able to do `",".split("a,b,c")`.  
There’s even a mnemonic. Think of “comma-separated values”.  
Well this is a “comma split string”.

Now there is a way with `CBOOCall.jl`:

```julia
julia> @eval Base import CBOOCall;
julia> @eval Base CBOOCall.@cbooify String (split,)

```

Then we have

```julia
julia> ",".split("a,b,c")
1-element Vector{SubString{String}}:
 ","

```

… uh, we can fix that

```julia
julia> @eval Base CBOOCall.@cbooify String (split=(x,y) -> split(y, x),)
julia> ",".split("a,b,c")
3-element Vector{SubString{String}}:
 "a"
 "b"
 "c"

```

Ahhhh… That’s much better than `split("a,b,c", ",")`! …  
I mean `split(",", "a,b,c")`.

… wait …, is, … it’s the other way around, right? Let’s consult the _Zen of CBOO_.

```python
>>> spl[TAB, TAB] # Bonk! Bonk! It's not there.
>>> from string import spl[TAB, TAB] # Bonk! Bonk! Not there either. Good.
>>> ','.split("a,b,c")
[',']
>>> 'a,b,c'.split(",")
['a', "b", 'c']

```

So the first way was correct. In any case, this is clearly the superior, intuitive, syntax for splitting strings.

Of course, you have to pay for this with a performance hit, right? How much is it?

Let’s pick a fast operation, and put it in the middle of a list, and swap parameter order for no reason.

```julia
julia> @eval Base CBOOCall.@cbooify Int64 (+, /, length, xor=(x,y)->xor(y,x), floor, rand)

```

The usual way

```julia
julia> @btime sum(xor(x,y) for (x, y) in zip(1:100, 101:200))
  2.134 ns (0 allocations: 0 bytes)
16856

```

The way of CBOO

```julia
julia> @btime sum(x.xor(y) for (x, y) in zip(1:100, 101:200))
  2.134 ns (0 allocations: 0 bytes)
16856

```

Why does this work ? Someone made searching for a literal `Symbol` in a `Tuple` of `Symbol`s very fast in order to make `NamedTuple`s fast.

```julia
julia> @btime in(3, (1,2,3))
  1.442 ns (0 allocations: 0 bytes)
true

julia> @btime in(:a, (:b, :c, :a))
  0.020 ns (0 allocations: 0 bytes)
true

```

(The for-real README gives the real motivation, which is to avoid namespace pollution)

---

<div class="post-metadata">

**Author:** ![Palli](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/palli/32/3380_2.png) [@Palli](https://discourse.julialang.org/u/Palli)\
**Post date:** [May 21, 2022, 3:50pm UTC](https://discourse.julialang.org/t/ann-cboocall/81420/2 "2022-05-21T15:50:33Z")

</div>

I think I get what the package does, just not the reasoning for the name CBOO[Call] and “`@cbooify`”

> which allows you to write the function call f(a::A, args…) as a.f(args…) as well. You can use it by adding a single line to your module. Using the alternative call syntax incurs no performance penalty.

This looks to me more like C++ [OO] syntax (I read it as CB - OO, still unclear why CB). Is it really better to abandon the usual multiple dispatch syntax? And why do you state:

> For example, in building quantum computing circuits programmatically, people really want to write circ.x(1)

---

<div class="post-metadata">

**Author:** ![jlapeyre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jlapeyre/32/4514_2.png) [@jlapeyre](https://discourse.julialang.org/u/jlapeyre)\
**Post date:** [May 21, 2022, 4:12pm UTC](https://discourse.julialang.org/t/ann-cboocall/81420/3 "2022-05-21T16:12:58Z")

</div>

> just not the reasoning for the name CBOO

Google this: cboo julia language

> Is it really better to abandon the usual multiple dispatch syntax

I was 1000% certain that would be in the first reply to this post. I forgot to add some sort of redirection channel to the post: There are several posts and probably hundreds of comments on why it’s not a good idea (and maybe a few in favor) to do this. I invite anyone who is interested to find those threads and read them and perhaps add any new insights they have. But, I respectfully request that comments in this post refrain from pursuing this topic. It would be a distraction… I don’t know, if someone really feels like they have to save the uninitiated from perdition, then a comment here with a link to such a discussion might be reasonable.

> And why do you state

That’s a good point. I could have been more thorough in the readme with a link to some of the many quantum-circuit building packages that do this. You could check out the software for building circuits from IBM, Google, AWS, Microsoft, etc.

EDIT: What I do think is on topic here is concrete proposals to solve the motivating problem given in the README in a different way. Other ideas have been suggested. For example, for the particular application linked there, [we tried several](https://github.com/Adgnitio/QuantumCircuits.jl/issues/28). You can certainly argue over the merits of the different approaches.

EDITED EDIT: I think more context will help: I don’t know if `@cbooify` will work out for `QuantumCircuits.jl` in the end. But, I wanted a package with a very simple interface in order to quickly switch it on and off.

---

<div class="post-metadata">

**Author:** ![linwaytin](https://avatars.discourse-cdn.com/v4/letter/l/898d66/32.png) [@linwaytin](https://discourse.julialang.org/u/linwaytin)\
**Post date:** [November 11, 2022, 7:29pm UTC](https://discourse.julialang.org/t/ann-cboocall/81420/4 "2022-11-11T19:29:53Z")

</div>

This is exactly what I want. Thanks!