C#•2y ago

✅ `with` expression does not work with `ValueTuple`

This code:

Foo foo = new();
Foo foo1 = foo with { Bar.Item1 = 1 };

record Foo
{
    public (int, int) Bar = (0, 0);
}

Foo foo = new();
Foo foo1 = foo with { Bar.Item1 = 1 };

record Foo
{
    public (int, int) Bar = (0, 0);
}

Gives The name 'Bar' does not exist in the current context on the second line? Why is this?

6 Replies

Thinker•2y ago

Bar is a field, not a property I assume with expressions only work with properties...? Or wait might be that you can't set tuple values like that

333fred•2y ago

With expressions do not allow setting nested values

palapapaOP•2y ago

Probably because if Bar is a reference type, then with becomes destructive, which is not what it promises

333fred•2y ago

Not really, we didn't allow it because we don't find it clear In this particular example, it's probably ok, but in general we didn't think so There are proposals around enhancements, but they also run into the issue of understandablility

Thinker•2y ago

You could probably do foo with { Bar = foo.Bar with { Item1 = 1 } }...?

palapapaOP•2y ago

I can

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✅ `with` expression does not work with `ValueTuple`