Explicitly invoking super.__ctor in a constructor does not count as calling a super constructor

[dlangBugzillaToGithub]

Ethan Watson reported this on 2018-05-20T17:20:39Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=18886

CC List

• Andrei Alexandrescu (@andralex)
• Adam D. Ruppe
• RazvanN

Description

Example code at https://run.dlang.io/is/Is9tAs

A workaround is to define a default constructor, as per https://run.dlang.io/is/mhM24Y

But this is just doubling up on work that I shouldn't need to do.

Came about because I was trying to explicitly invoke a templated constructor in a base class. Simple example at https://run.dlang.io/is/XAsoyo

[dlangBugzillaToGithub]

andrei (@andralex) commented on 2018-06-07T20:16:51Z

This isn't a bug. Calling __ctor explicitly is advanced usage, not part of the usual typechecking. Is there any strong reason to keep this open? Is it preventing some use case?

[dlangBugzillaToGithub]

destructionator commented on 2018-06-07T20:22:22Z

The templated constructor use case looks valid, but the language doesn't allow you to explicitly call `super!(args)`...

[dlangBugzillaToGithub]

andrei (@andralex) commented on 2018-06-07T20:23:17Z

Then we should allow that call.

[dlangBugzillaToGithub]

destructionator commented on 2018-06-07T20:25:34Z

yeah i agree.

[dlangBugzillaToGithub]

destructionator commented on 2018-06-07T20:26:10Z

errr and also while we're at it, perhaps calling `this!(args)` as well, for forwarding to another ctor in the same class.

[dlangBugzillaToGithub]

gooberman commented on 2018-06-07T21:09:00Z

The code I'm invoking in my current codebase extracts type data from the template parameter for object management.

Another workaround would probably be to have a templated this( Type )( ref Type val ) in the base class and then call super( this ) from the derived class. Which feels as janky as it looks.

Supporting super!( Args )() would be far more preferable, won't even need to do a __ctor hack then.