Re: Dual conditions in D and Python

[Meta via Digitalmars-d-learn]

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))
{
    //...
}