helicon
Using macros in guard clauses
Hey!
I have a function
@doc """
Check if given id has 64-bit size
Examples:
> MyModule.has_64_bit_size(132700114308300801)
true
> MyModule.has_64_bit_size(35)
false
"""
def has_64_bit_size(id) do
bit_size(:binary.encode_unsigned(id)) == 64
end
I want to implement defmacro has_64_bit_size. What should it look like?
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First Post!
kip
Something like this:
I’m trying to thing of a use case where a macro would make more sense than just using the function you define but its not clear to me. Generally speaking, the first rule of macros in Elixir is don’t use macros. But of course when you need one, you need one!
Most Liked
hauleth
You do not need such magic value:
LostKobrakai
Guards can only be composed of guard-safe functions and also with elixir >= 1.6 you want to use
defguardinstead of a macro to compose those.:binary.encode_unsigned/1is not guard-safe though, so you cannot do what you want to do in a guard.helicon
Last Post!
kip
Oh yes, much better solution! Didn’t realise that
bsland friends were guard safe.