On Thursday, 21 May 2015 at 19:05:16 UTC, Steven Schveighoffer wrote:
> On 5/21/15 12:57 PM, Dennis Ritchie wrote:
>> Hi,
>> In Python I can write this:
>>
>> if (4 <= 5 <= 6):
>>     print ("OK")
>> -----
>> http://rextester.com/NNAM70713
>>
>> In D, I can only write this:
>>
>> import std.stdio;
>>
>> void main() {
>>
>>     if (4 <= 5 && 5 <= 6)
>>         puts("OK");
>> }
>> -----
>> http://rextester.com/FICP83173
>>
>> I wanted to ask what is the reason? Maybe the program on Python's slower
>> because of this? Or legacy C/C++ affected D?
>
>
> There is this possibility:
>
> switch(5){
>    case 4: .. case 6:
> }
>
> You could also make some nifty abuse-of-syntax types:
>
> struct Between(T)
> {
>    T low;
>    T high;
>    bool opBinaryRight!(op : "in")(T val) { return val >= low && val <= high;}
> }
>
> auto between(T)(T low, T high) { return Between!T(low, high); }
>
> if(5 in between(4, 6))
>
> :)
>
> -Steve

All we need is user-defined opIs and then we're really cooking with gas.

if (5 is between(4, 6))
{
    //...
}

On 05/21/2015 12:44 PM, Meta wrote:

> All we need is user-defined opIs and then we're really cooking with gas.
>
> if (5 is between(4, 6))
> {
>      //...
> }
>

We're almost there. :)

bool is_between(T0, T1, T2)(T0 what, T1 min, T2 max)
{
    return (what >= min) && (what <= max);
}

void main()
{
    if (5.is_between(4, 6)) {
        // ...
    }
}

Ali

On Thursday, 21 May 2015 at 21:35:22 UTC, Ali Çehreli wrote:
> We're almost there. :)
>
> bool is_between(T0, T1, T2)(T0 what, T1 min, T2 max)
> {
>     return (what >= min) && (what <= max);
> }
>
> void main()
> {
>     if (5.is_between(4, 6)) {
>         // ...
>     }
> }
>
> Ali

A condition is that if, for example, that? :)

if (5 > 2 > -9 > -13 < 10 == 10 < 21 != 45):
    print("OK")
-----
http://rextester.com/JSC75231

import std.stdio;

void main()
{
    if (5 > 2 &&
	2 > -9 &&
	-9 > -13 &&
	-13 < 10 &&
	10 == 10 &&
	10 < 21 &&
	21 != 45)
	writeln("OK");
}
-----
http://rextester.com/AZFL70044

On Thursday, 21 May 2015 at 23:14:47 UTC, Dennis Ritchie wrote:
> On Thursday, 21 May 2015 at 21:35:22 UTC, Ali Çehreli wrote:
>> We're almost there. :)
>>
>> bool is_between(T0, T1, T2)(T0 what, T1 min, T2 max)
>> {
>>    return (what >= min) && (what <= max);
>> }
>>
>> void main()
>> {
>>    if (5.is_between(4, 6)) {
>>        // ...
>>    }
>> }
>>
>> Ali
>
> A condition is that if, for example, that? :)
>
> if (5 > 2 > -9 > -13 < 10 == 10 < 21 != 45):
>     print("OK")

this looks like gibberish upon first sight and is not something I'd want to see in code I inherit.

On 5/21/15 2:35 PM, Ali Çehreli wrote:
> On 05/21/2015 12:44 PM, Meta wrote:
>
>> All we need is user-defined opIs and then we're really cooking with gas.
>>
>> if (5 is between(4, 6))
>> {
>>      //...
>> }
>>
>
> We're almost there. :)
>
> bool is_between(T0, T1, T2)(T0 what, T1 min, T2 max)
> {
>      return (what >= min) && (what <= max);
> }
>
> void main()
> {
>      if (5.is_between(4, 6)) {
>          // ...
>      }
> }

In fact we'll be there with 2.068:

http://dlang.org/phobos-prerelease/std_algorithm_sorting.html#.ordered

if (ordered(4, 5, 6)) { ... }
if (strictlyOrdered(4, 5, 6)) { ... }


Andrei

On Sat, 2015-05-23 at 10:17 -0700, Andrei Alexandrescu via Digitalmars-d-learn wrote:
> […]
> 
> if (ordered(4, 5, 6)) { ... }
> if (strictlyOrdered(4, 5, 6)) { ... }

So the latter means the integers have to lashed as well as ordered?  ; -)

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On Saturday, 23 May 2015 at 17:17:17 UTC, Andrei Alexandrescu wrote:
> On 5/21/15 2:35 PM, Ali Çehreli wrote:
>> On 05/21/2015 12:44 PM, Meta wrote:
>>
>>> All we need is user-defined opIs and then we're really cooking with gas.
>>>
>>> if (5 is between(4, 6))
>>> {
>>>     //...
>>> }
>>>
>>
>> We're almost there. :)
>>
>> bool is_between(T0, T1, T2)(T0 what, T1 min, T2 max)
>> {
>>     return (what >= min) && (what <= max);
>> }
>>
>> void main()
>> {
>>     if (5.is_between(4, 6)) {
>>         // ...
>>     }
>> }
>
> In fact we'll be there with 2.068:
>
> http://dlang.org/phobos-prerelease/std_algorithm_sorting.html#.ordered
>
> if (ordered(4, 5, 6)) { ... }
> if (strictlyOrdered(4, 5, 6)) { ... }
>
>
> Andrei

I didn't realize this got pulled, I remember it being discussed a while back on the general NG. Good addition.