I am thinking of a construct to make initialization of large, complex structures with named members easier. Some ideas:
with expression
class Config {
var name: string;
var size: int;
var doMore: bool;
var extraThings: Array<int>;
}
def x = Config.new() with {
name = "foo";
size = 44;
doMore = false;
extraThings = [88, 99, 1000];
};
The idea of the with expression is that it takes an expression on the left and applies the updates to the fields given in the curlies { ... }. For class types with mutable members, it takes an object, mutates the original object and returns it. For tuples, data types, or ADTs, it would create a new value with the updated fields.
It allows for having lots of parameters via a config object:
class Args { ... }
def m(x: Args) {
...
}
var r1 = m(Args.new() with { name = "string"; size = 66; });
// or, eliding the .new():
var r2 = m(Args with {name = "myname"; size = 777; });
withexpressionThe idea of the
withexpression is that it takes an expression on the left and applies the updates to the fields given in the curlies{ ... }. For class types with mutable members, it takes an object, mutates the original object and returns it. For tuples, data types, or ADTs, it would create a new value with the updated fields.It allows for having lots of parameters via a config object:
Wdyt?
Originally posted by @titzer in https://github.com/titzer/virgil/discussions/122#discussioncomment-4999342