digitalmars.D.learn - Check if template has been passed a reference type or value type?
- 1967 (8/8) Jun 07 2015 I've got a template that takes in a type. Sometimes the type is a
- "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> (6/14) Jun 07 2015 You can directly check whether it allows comparison with null:
- sigod (3/18) Jun 24 2015 Don't forget [`Nullable`][0] type, which won't pass this check.
- Gary Willoughby (3/11) Jun 25 2015 A simple test:
I've got a template that takes in a type. Sometimes the type is a class, sometimes a struct, sometimes just an int. It doesn't much matter what it is, but if it's a reference type I need to check if it's null so I can make it not null before using it. I get an error if I try to check if a value type is null so I'd like to put a "static if" to check if the type passed to the template is a nullable one so I can avoid checking the value types passed in. What do I have to do to check for nullability?
Jun 07 2015
On Sunday, 7 June 2015 at 15:17:27 UTC, 1967 wrote:I've got a template that takes in a type. Sometimes the type is a class, sometimes a struct, sometimes just an int. It doesn't much matter what it is, but if it's a reference type I need to check if it's null so I can make it not null before using it. I get an error if I try to check if a value type is null so I'd like to put a "static if" to check if the type passed to the template is a nullable one so I can avoid checking the value types passed in. What do I have to do to check for nullability?You can directly check whether it allows comparison with null: static if(is(typeof(value is null) : bool)) { if(value is null) ... }
Jun 07 2015
On Sunday, 7 June 2015 at 15:39:17 UTC, Marc Schütz wrote:On Sunday, 7 June 2015 at 15:17:27 UTC, 1967 wrote:Don't forget [`Nullable`][0] type, which won't pass this check.I've got a template that takes in a type. Sometimes the type is a class, sometimes a struct, sometimes just an int. It doesn't much matter what it is, but if it's a reference type I need to check if it's null so I can make it not null before using it. I get an error if I try to check if a value type is null so I'd like to put a "static if" to check if the type passed to the template is a nullable one so I can avoid checking the value types passed in. What do I have to do to check for nullability?You can directly check whether it allows comparison with null: static if(is(typeof(value is null) : bool)) { if(value is null) ... }
Jun 24 2015
On Sunday, 7 June 2015 at 15:17:27 UTC, 1967 wrote:I've got a template that takes in a type. Sometimes the type is a class, sometimes a struct, sometimes just an int. It doesn't much matter what it is, but if it's a reference type I need to check if it's null so I can make it not null before using it. I get an error if I try to check if a value type is null so I'd like to put a "static if" to check if the type passed to the template is a nullable one so I can avoid checking the value types passed in. What do I have to do to check for nullability?A simple test: http://dpaste.dzfl.pl/3b8c5a0bb69c
Jun 25 2015