enum of struct not calling constructor

Andrej Mitrovic none at none.none
Tue Jan 18 08:44:02 PST 2011


Example 1:

import std.stdio;

enum WindowSizes : QSize
{
    Minimum = QSize(10)
}

struct QSize
{
    int store;
    this(int x)
    {
        store = x + 10;
    }
}

void main()
{
    auto foo = WindowSizes.Minimum;
    assert(foo.store == 10);  // What?

    auto bar = QSize(10);
    assert(bar.store == 20);
}

It appears the constructor is never called for the enum. It does field by field assignments instead, just take a look at this case:

import std.stdio;

enum WindowSizes : Inverted
{
    Minimum = Inverted(10, 20)
}

struct Inverted
{
    int x;
    int y;
    this(int in_x, int in_y)
    {
        x = in_y;
        y = in_x;
    }
}

void main()
{
    auto foo = WindowSizes.Minimum;
    assert(foo.x == 10);
    assert(foo.y == 20);

    auto bar = Inverted(10, 20);
    assert(bar.x == 20);
    assert(bar.y == 10);
}

As can be seen, this could be a potential source of bugs. Should I file it?


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