Well, the whole problem is that = can't be AST-overloaded. That would be the
best and most nimish solution. However, I found three other solutions as well,
one of which I will quote. Sadly, all three require patterns so if you use
\--patterns:off, the checks will be disabled. Here it comes, the best solution
I found:
type Person = object
first, last: string
proc newPerson(first, last: string): Person =
result.first = first
result.last = last
# Surprisingly, this is needed for patterns to notice p=src as an operator
call.
proc `=`*(d: var Person; src: Person) = system.`=`(d, src)
# We assume moving is a copy from call.
template personEqErr*{`=`(p, i)}(p: Person, i: Person{lit|lvalue|`let`}) =
{.error: "Person doesn't allow implicit copy".}
let person1: Person = newPerson("John", "Doe")
let person2: Person = Person(first: "John", last: "Doe")
#let person3 = person1 # error!
echo person1.first, " ", person1.last
echo person2.first, " ", person2.last
If you'd like to disable built-in constructors too (i.e. only call
initialization), then here you go:
type Person = object
first, last: string
proc newPerson(first, last: string): Person =
result.first = first
result.last = last
# Surprisingly, this is needed for patterns to notice p=src as an operator
call.
proc `=`*(d: var Person; src: Person) = system.`=`(d, src)
# We assume moving is a copy from call.
template personEqErr*{`=`(p, i)}(p: Person, i: Person{~call}) =
{.error: "Person doesn't allow implicit copy".}
let person1: Person = newPerson("John", "Doe")
#let person2: Person = Person(first: "John", last: "Doe") # error!
#let person3 = person1 # error!
echo person1.first, " ", person1.last
