Gilou06
Hello,
I keep using a paradigme using a homemade function to make my life easier when piping.
I wonder if there is a better way to achieve the same result, maybe something already part of Elixir language.
Instead of writing a tailored maybe_dothat() function, I prefer a generic maybe_do() wrap function around a do_that() function.
Here is the may_be/1 wrapper.
def maybe_do(pipe_value, condition, function)
when is_boolean(condition) and is_function(function) do
if condition do
function.(pipe_value)
else
pipe_value
end
end
Let’s say I want to always call do_this/1 on a socket and do_that/1 but only if my_bool is true, else socket rest unchanged.
I write it this way:
socket
|> maybe_do(my_bool, &do_this/1)
|> do_that()
Your insights are welcome.
Jean-yves 
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greven
There is not such construct in Elixir that I know of, there is tap/2 to perform a side effect but the original value is the one being pipped, there is also then/2 but here is the function return in the second argument that is being pipped instead.
So I guess your solution is fine if you find yourself repeating that pattern a lot.
dimitarvp
As the other poster said,
tapandthencover a lot of needs, and also yeah if it’s more convenient for you to use your own function then please don’t feel bad about it! It’s very normal.People use their own functions a lot when you need to go through a series of validations, for example. It’s expected to do it like that in many teams even.
cloudytoday
You can do the same with
case:Alternatively you can write a macro that supports holes, lets say you call it
p:Doesn’t have to be exactly like this ofc, you can define it to be whatever you like the most. Just giving an example here. I actually have a bunch of these in my helpers libs. Edit: or, even better, you can also extend the pipe itself with this macro.
sodapopcan
If you’re really talking about a socket and only talking about a couple of functions, I would use a live hook like
on_mountorattach_hookalong with anif.Gilou06
It’s about coding GUI behavior (Phoenix/Surface) based on user actions.
Gilou06
Yes, it does the same, but I like the compactness of maybe_do(…). It reads nicely.
cloudytoday
Yes agree,
caseis a bit lengthy.fuelen
Here is a related discussion https://groups.google.com/g/elixir-lang-core/c/OGRW7R74ArY/
dimitarvp
An alternative implementation:
Gilou06
That’s way better, thank you!
I still fear that my approach maybe a code smell.
I mean, I must not be the first one to need to chain (pipe) functions based on some conditions that are not directly part of the piped data.
This is typically true with GUI events. You want to reflect the actions in the socket (the piped data), but the event itself is not part of that socket.
An option would be to add the events to the piped data, piping {event,socket} rather than the plain socket.
Anyway, thank you again.