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digitalmars.D - Re: Using typedefed types as covariant return types

reply Rick Mann <rmann-d-lang latencyzero.com> writes:
Bill Baxter Wrote:

 What are you reading that makes you think CFStringRef is "derived" from 
 CFTypeRef?

It seems to be implied by the "Implicit Conversions" section of <http://www.digitalmars.com/d/type.html>: "A typedef or enum can be implicitly converted to its base type, but going the other way requires an explicit conversion. "
Feb 11 2007
parent reply Bruno Medeiros <brunodomedeiros+spam com.gmail> writes:
Rick Mann wrote:
 Bill Baxter Wrote:
 
 What are you reading that makes you think CFStringRef is "derived" from 
 CFTypeRef?

It seems to be implied by the "Implicit Conversions" section of <http://www.digitalmars.com/d/type.html>: "A typedef or enum can be implicitly converted to its base type, but going the other way requires an explicit conversion. "

Implicitly convertible doesn't mean a type is a subtype of another. Altough in this case of typedef and enums I think they could be subtypes of the base type. -- Bruno Medeiros - MSc in CS/E student http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D
Feb 12 2007
parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Bruno Medeiros wrote:
 Rick Mann wrote:
 Bill Baxter Wrote:
 "A typedef or enum can be implicitly converted to its base type, but 
 going the other way requires an explicit conversion. "

Implicitly convertible doesn't mean a type is a subtype of another. Altough in this case of typedef and enums I think they could be subtypes of the base type.

Perhaps he meant the "to its base type" part? I could see someone mixing that up with the same term used in class hierarchies...
Feb 12 2007
next sibling parent Bruno Medeiros <brunodomedeiros+spam com.gmail> writes:
Frits van Bommel wrote:
 Bruno Medeiros wrote:
 Rick Mann wrote:
 Bill Baxter Wrote:
 "A typedef or enum can be implicitly converted to its base type, but 
 going the other way requires an explicit conversion. "

Implicitly convertible doesn't mean a type is a subtype of another. Altough in this case of typedef and enums I think they could be subtypes of the base type.

Perhaps he meant the "to its base type" part? I could see someone mixing that up with the same term used in class hierarchies...

True enough, that may cause some confusion. -- Bruno Medeiros - MSc in CS/E student http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D
Feb 12 2007
prev sibling parent Rick Mann <rmann-d-lang latencyzero.com> writes:
Frits van Bommel Wrote:

 Bruno Medeiros wrote:
 Rick Mann wrote:
 Bill Baxter Wrote:
 "A typedef or enum can be implicitly converted to its base type, but 
 going the other way requires an explicit conversion. "

Implicitly convertible doesn't mean a type is a subtype of another. Altough in this case of typedef and enums I think they could be subtypes of the base type.

Perhaps he meant the "to its base type" part? I could see someone mixing that up with the same term used in class hierarchies...

In that case, I'd like to make it a feature request. It seems only natural to be able to use typedefs in this manner. Should I file a formal request via bug?
Feb 17 2007