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digitalmars.D.learn - Subrange type

reply Herbert <ht softdesign.de> writes:
How can I create a subrange type, for example ushort DiceValue {1 
.. 6}?
Jan 27 2020
next sibling parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
On 1/27/20 3:06 PM, Herbert wrote:

 How can I create a subrange type, for example ushort DiceValue {1 ... 6}?


D doesn't have a "Range" type like this. But you can use ranges of 
different types by typing the literals. Note that D numeric ranges are 
always exclusive at the upper end.

e.g.:

ushort(1) .. ushort(6+1)

-Steve
Jan 27 2020
parent reply Herbert <ht softdesign.de> writes:
On Monday, 27 January 2020 at 20:15:33 UTC, Steven Schveighoffer 
wrote:

 On 1/27/20 3:06 PM, Herbert wrote:

 How can I create a subrange type, for example ushort DiceValue 
 {1 ... 6}?


 D doesn't have a "Range" type like this. But you can use ranges 
 of different types by typing the literals. Note that D numeric 
 ranges are always exclusive at the upper end.

 e.g.:

 ushort(1) .. ushort(6+1)

 -Steve


Thank you Steven!

How can I have a function parameter with this type (DiceValue)?
Jan 27 2020
next sibling parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Mon, Jan 27, 2020 at 09:15:58PM +0000, Herbert via Digitalmars-d-learn wrote:
[...]

 How can I have a function parameter with this type (DiceValue)?


Just take an integer type and add a contract that enforces range. For
example:

	auto myFunc(int diceValue)
		in (diceValue >= 1 && diceValue <= 6)
	{
		// do stuff here
	}


T

-- 
Which is worse: ignorance or apathy? Who knows? Who cares? -- Erich Schubert
Jan 27 2020
prev sibling parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 1/27/20 1:15 PM, Herbert wrote:

 On Monday, 27 January 2020 at 20:15:33 UTC, Steven Schveighoffer wrote:

 On 1/27/20 3:06 PM, Herbert wrote:

 How can I create a subrange type, for example ushort DiceValue {1 ... 
 6}?


 D doesn't have a "Range" type like this. But you can use ranges of 
 different types by typing the literals. Note that D numeric ranges are 
 always exclusive at the upper end.

 e.g.:

 ushort(1) .. ushort(6+1)

 -Steve


 
 Thank you Steven!
 
 How can I have a function parameter with this type (DiceValue)?
 


There is also iota() than generates a range:

import std.stdio;
import std.range;

void foo(R)(R range) {
   pragma(msg, "Element type: ", ElementType!R);

   writefln!"Using as a range:\n%-(%s\n%)"(range);

   writeln("Using in a foreach loop:");

   foreach (element; range) {
     writeln(element);
   }
}

void main() {
   auto range = iota(ushort(1), ushort(7));
   foo(range);
}

The output:

Using as a range:
1
2
3
4
5
6
Using in a foreach loop:
1
2
3
4
5
6

Ali
Jan 27 2020
parent reply Herbert <ht softdesign.de> writes:
On Monday, 27 January 2020 at 22:05:57 UTC, Ali Çehreli wrote:

 On 1/27/20 1:15 PM, Herbert wrote:

 On Monday, 27 January 2020 at 20:15:33 UTC, Steven 
 Schveighoffer wrote:

 On 1/27/20 3:06 PM, Herbert wrote:

 [...]


 D doesn't have a "Range" type like this. But you can use 
 ranges of different types by typing the literals. Note that D 
 numeric ranges are always exclusive at the upper end.

 e.g.:

 ushort(1) .. ushort(6+1)

 -Steve


 
 Thank you Steven!
 
 How can I have a function parameter with this type (DiceValue)?
 


 There is also iota() than generates a range:

 import std.stdio;
 import std.range;

 void foo(R)(R range) {
   pragma(msg, "Element type: ", ElementType!R);

   writefln!"Using as a range:\n%-(%s\n%)"(range);

   writeln("Using in a foreach loop:");

   foreach (element; range) {
     writeln(element);
   }
 }

 void main() {
   auto range = iota(ushort(1), ushort(7));
   foo(range);
 }

 The output:

 Using as a range:
 1
 2
 3
 4
 5
 6
 Using in a foreach loop:
 1
 2
 3
 4
 5
 6

 Ali


wow, pragma, import ...
only to declare a subrange type, something so simple and natural

I could use it in many functions as a parameter type with one 
single simple declaration.

It's a pitty.
Jan 28 2020
parent =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 1/28/20 1:55 AM, Herbert wrote:


 wow, pragma,


pragma was to indicate the type of elements at compile time.


 import ...


Yes, iota is a Phobos feature, part of a module.


 only to declare a subrange type, something so simple and natural


Some languages think so.


 I could use it in many functions as a parameter type with one single
 simple declaration.


Sorry for jumping in the conversation like that but no, it's not a 
subrange type.


 It's a pitty.


My apologies...

Ali
Jan 28 2020
prev sibling parent Paul Backus <snarwin gmail.com> writes:
On Monday, 27 January 2020 at 20:06:14 UTC, Herbert wrote:

 How can I create a subrange type, for example ushort DiceValue 
 {1 .. 6}?


Probably the closest you can get is a struct with an invariant:

import std.traits: isOrderingComparable;

struct Subrange(T, T min, T max)
     if (isOrderingComparable!T)
{
     private T value_ = min;
     invariant(min <= value && value <= max);

     this(T t) { value_ = t; }

     T value() { return value_; }
     alias value this;

     ref Subrage opAssign(T t) { value_ = t; return this; }
}
Jan 27 2020