• tcak (8/8) Apr 28 2015 Is there any way to define a variable or an attribute as
• Justin Whear (14/23) Apr 28 2015 1. I wouldn't worry too much about the performance--compiling with gdc o...
• Baz (28/36) Apr 28 2015 an quick attempt:

"tcak" <tcak gmail.com> writes:

Is there any way to define a variable or an attribute as 
read-only without defining a getter function/method for it?

Thoughts behind this question are:
1. For every reading, another function call process for CPU while 
it could directly read the value from memory.

2. Repetition of same name for variable and getVariableName. 
(Some might not agree with this but I like the code when it looks 
nice.)

Justin Whear <justin economicmodeling.com> writes:

On Tue, 28 Apr 2015 19:30:04 +0000, tcak wrote:

 Is there any way to define a variable or an attribute as read-only
 without defining a getter function/method for it?
 
 Thoughts behind this question are:
 1. For every reading, another function call process for CPU while it
 could directly read the value from memory.
 
 2. Repetition of same name for variable and getVariableName. (Some might
 not agree with this but I like the code when it looks nice.)

1. I wouldn't worry too much about the performance--compiling with gdc or 
ldc with inlining should reduce it to a simple access.
2. You can clean it up if it annoys you with something like this:

mixin template readonly(T, string name)
{
    mixin(`private T _`~name~`;T `~name~`() property{return _`~name~`;}`);
}

Use it like:

class Foo
{
    // injects a private int _x, public int x()
    mixin readonly!(int, "x");
}

"Baz" <bb.temp gmx.com> writes:

On Tuesday, 28 April 2015 at 19:30:06 UTC, tcak wrote:
 Is there any way to define a variable or an attribute as 
 read-only without defining a getter function/method for it?

 Thoughts behind this question are:
 1. For every reading, another function call process for CPU 
 while it could directly read the value from memory.

 2. Repetition of same name for variable and getVariableName. 
 (Some might not agree with this but I like the code when it 
 looks nice.)

an quick attempt:

---
union ReadOnlyOutside(T)
{
     alias value this;
     private T _value;
     public const T value;
}
---

when you declare such a variable inside a struct or a class, the 
code located in another module won't be able to modify the value:

module1:

---
struct Foo
{
     ReadOnlyOutside!size_t roField;
}
---

module2:

void something(ref Foo foo)
{
     writeln(foo.roField); // OK
     writeln(foo.roField.value); // OK
     foo.roField = 1; // FAIL
     foo.roField.value = 1,// FAIL (because const).
     foo.roField._value = 1,// FAIL (because not visible).
}