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digitalmars.D.learn - Cannot implicitly convert expression (struct this)

reply Andre Pany <andre s-e-a-p.de> writes:
Hi,

I created a custom type which enables me to have enums which have 
in their initial state, the init value of their base type. 
Something similiar to Nullable...

enum Reason : string {CO = "Co", FU = "Fu", CA = "Ca"}
struct TestStruct {InitialEnum!Reason reason;}

This line raises the error:
TestStruct s2 = TestStruct(Reason.FU);

 Error: cannot implicitly convert expression ("Fu") of type 
 Reason to InitialEnum!(Reason)




While this line is working fine:
TestStruct s1 = {reason: Reason.FU};

What do I miss?

Kind regards
André

struct InitialEnum(T)
{
	import std.traits: OriginalType, EnumMembers;
	import std.conv: to;
	
	private T _value;
	private bool _isEmpty = true;
	alias EnumBaseType = OriginalType!T;
	
	 property EnumBaseType baseTypeValue() { return (_isEmpty) ? 
EnumBaseType.init : _value; }
	 property T value()	{ return _value; }
	 property bool isEmpty() { return _isEmpty;	}
	
	alias baseTypeValue this;
	
	void opAssign(EnumBaseType value)
	{
		if (value == EnumBaseType.init)
		{
			_isEmpty = true;
			return;
		}
		
		foreach (member; EnumMembers!T)
		{
			if (value == member)
			{
				_value = member;
				_isEmpty = false;
				return;
			}		
		}
		throw new Exception("Value "~value.to!string~" is not a valid 
enum value");
	}

	this(T t)
	{
		_isEmpty = false;
		_value = t;
	}
	
	this(EnumBaseType value)
	{
		opAssign(value);
	}
}
Jun 22 2017
parent reply Kagamin <spam here.lot> writes:
On Thursday, 22 June 2017 at 09:57:44 UTC, Andre Pany wrote:

 This line raises the error:
 TestStruct s2 = TestStruct(Reason.FU);

 Error: cannot implicitly convert expression ("Fu") of type 
 Reason to InitialEnum!(Reason)




 While this line is working fine:
 TestStruct s1 = {reason: Reason.FU};


I think these should be equivalent, report a bug.
Jun 23 2017
parent Andre Pany <andre s-e-a-p.de> writes:
On Friday, 23 June 2017 at 15:52:10 UTC, Kagamin wrote:

 On Thursday, 22 June 2017 at 09:57:44 UTC, Andre Pany wrote:

 This line raises the error:
 TestStruct s2 = TestStruct(Reason.FU);

 Error: cannot implicitly convert expression ("Fu") of type 
 Reason to InitialEnum!(Reason)




 While this line is working fine:
 TestStruct s1 = {reason: Reason.FU};


 I think these should be equivalent, report a bug.


Issue 17552 created:
http://forum.dlang.org/post/mailman.3688.1498412595.31550.digitalmars-d-bugs puremagic.com

Kind regards
André
Jul 05 2017