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digitalmars.D.learn - property for simple methods?

reply Vladimirs Nordholm <v vladde.net> writes:
Heyo.

I have a struct with a couple "property" methods, like:

     struct A
     {
         auto foo(int bar) { /* do something */ }
     }

Is there any reason for me to add the  property tags for the 
method? The following code compiles just fine with the struct 
above

     A a = A();
     a.foo = 42; // no  property tag for `foo(int bar);` yet works

Best regards,
Vladimirs Nordholm
Apr 02 2018
parent reply Dennis <dkorpel gmail.com> writes:
On Monday, 2 April 2018 at 13:57:14 UTC, Vladimirs Nordholm wrote:

 Is there any reason for me to add the  property tags for the 
 method?


A list of things the  property tag does can be found here:
https://dlang.org/spec/function.html#property-functions

This behavior is particularly useful for generic code:
"For the expression typeof(exp) where exp is an  property 
function, the type is the return type of the function, rather 
than the type of the function."

Before I knew about this, I wrote this template to get the type 
of 'field', because typeof(field) would return 'int()' instead of 
'int' when it was a getter function without  property.

```
template ReturnOrValueType(type)
{
	static if (isSomeFunction!(type.field)) {
		alias ReturnOrValueType = ReturnType!(typeof(type.field));
	}
	else {
		alias ReturnOrValueType = typeof(type.field);
	}
}
```
Apr 02 2018
parent reply Vladimirs Nordholm <v vladde.net> writes:
On Monday, 2 April 2018 at 14:20:49 UTC, Dennis wrote:

 On Monday, 2 April 2018 at 13:57:14 UTC, Vladimirs Nordholm 
 wrote:

 Is there any reason for me to add the  property tags for the 
 method?


 A list of things the  property tag does can be found here:
 https://dlang.org/spec/function.html#property-functions

 This behavior is particularly useful for generic code:
 "For the expression typeof(exp) where exp is an  property 
 function, the type is the return type of the function, rather 
 than the type of the function."

 Before I knew about this, I wrote this template to get the type 
 of 'field', because typeof(field) would return 'int()' instead 
 of 'int' when it was a getter function without  property.

 ```
 template ReturnOrValueType(type)
 {
 	static if (isSomeFunction!(type.field)) {
 		alias ReturnOrValueType = ReturnType!(typeof(type.field));
 	}
 	else {
 		alias ReturnOrValueType = typeof(type.field);
 	}
 }
 ```


Ah! First time I read the docs I didn't understand the 
typeof(exp) explanation, but yours made me understand that part.

Do you think I should I omit the  property tag, if the only 
wanted behaviour is to set a value (`foo.bar = "baz";`) ?
Apr 02 2018
next sibling parent reply Seb <seb wilzba.ch> writes:
On Monday, 2 April 2018 at 14:51:57 UTC, Vladimirs Nordholm wrote:

 On Monday, 2 April 2018 at 14:20:49 UTC, Dennis wrote:

 On Monday, 2 April 2018 at 13:57:14 UTC, Vladimirs Nordholm 
 wrote:

 Is there any reason for me to add the  property tags for the 
 method?


 A list of things the  property tag does can be found here:
 https://dlang.org/spec/function.html#property-functions

 This behavior is particularly useful for generic code:
 "For the expression typeof(exp) where exp is an  property 
 function, the type is the return type of the function, rather 
 than the type of the function."

 Before I knew about this, I wrote this template to get the 
 type of 'field', because typeof(field) would return 'int()' 
 instead of 'int' when it was a getter function without 
  property.

 ```
 template ReturnOrValueType(type)
 {
 	static if (isSomeFunction!(type.field)) {
 		alias ReturnOrValueType = ReturnType!(typeof(type.field));
 	}
 	else {
 		alias ReturnOrValueType = typeof(type.field);
 	}
 }
 ```


 Ah! First time I read the docs I didn't understand the 
 typeof(exp) explanation, but yours made me understand that part.

 Do you think I should I omit the  property tag, if the only 
 wanted behaviour is to set a value (`foo.bar = "baz";`) ?


Yes I would omit  proporty if you don't need it as it isn't 
really useful at the moment.
There's a DIP to fix it and make it more powerful though:

https://github.com/dlang/DIPs/pull/97

And if you are looking for  read,  write limitations the 
accessors library might be interesting to you:

https://code.dlang.org/packages/accessors
Apr 02 2018
parent Vladimirs Nordholm <v vladde.net> writes:
On Monday, 2 April 2018 at 15:05:04 UTC, Seb wrote:

 On Monday, 2 April 2018 at 14:51:57 UTC, Vladimirs Nordholm 
 wrote:

 On Monday, 2 April 2018 at 14:20:49 UTC, Dennis wrote:

 [...]


 Ah! First time I read the docs I didn't understand the 
 typeof(exp) explanation, but yours made me understand that 
 part.

 Do you think I should I omit the  property tag, if the only 
 wanted behaviour is to set a value (`foo.bar = "baz";`) ?


 Yes I would omit  proporty if you don't need it as it isn't 
 really useful at the moment.
 There's a DIP to fix it and make it more powerful though:

 https://github.com/dlang/DIPs/pull/97

 And if you are looking for  read,  write limitations the 
 accessors library might be interesting to you:

 https://code.dlang.org/packages/accessors


Nice read, and the library seems interesting 👍
Apr 03 2018
prev sibling parent reply Dennis <dkorpel gmail.com> writes:
On Monday, 2 April 2018 at 14:51:57 UTC, Vladimirs Nordholm wrote:

 Do you think I should I omit the  property tag, if the only 
 wanted behaviour is to set a value (`foo.bar = "baz";`) ?


You're probably fine either way, it's mostly for making your 
intention clear. Jonathan M Davis made a great explanation:
(https://forum.dlang.org/post/mailman.709.1481234980.9448.digitalmars-d-learn puremagic.com)
Apr 02 2018
parent Vladimirs Nordholm <v vladde.net> writes:
On Monday, 2 April 2018 at 15:15:05 UTC, Dennis wrote:

 On Monday, 2 April 2018 at 14:51:57 UTC, Vladimirs Nordholm 
 wrote:

 Do you think I should I omit the  property tag, if the only 
 wanted behaviour is to set a value (`foo.bar = "baz";`) ?


 You're probably fine either way, it's mostly for making your 
 intention clear. Jonathan M Davis made a great explanation:
 (https://forum.dlang.org/post/mailman.709.1481234980.9448.digitalmars-d-learn puremagic.com)


His reasoning is the same as mine. I only have the  property as 
documentation :)
Apr 03 2018