• Rodolfo Borges (11/11) Jun 14 2005 http://www.digitalmars.com/d/statement.html#foreach
• Ben Hinkle (23/34) Jun 14 2005 The issue is that [1,2,3,4] isn't parsed as an expression returning a
• Uwe Salomon (4/4) Jun 14 2005 Perhaps you should add that this is a very cumbersome and slow approach....
• Ben Hinkle (4/6) Jun 14 2005 why not? Do you mean that it allocates memory every time you call toda? ...
• Uwe Salomon (13/19) Jun 14 2005 Yes, that's exactly what i mean. I would suggest that:
• Ben Hinkle (8/26) Jun 14 2005 I assumed the OP knew about for loops and they explicitly said they knew...
• Uwe Salomon (3/7) Jun 14 2005 You're right, of course. I forgot about that.
• pragma (3/12) Jun 14 2005 Ben, just a thought: are you 100% certain that you *must* dup the array?
• Ben Hinkle (5/18) Jun 14 2005 From http://www.digitalmars.com/d/function.html#variadic it says it is a...
• Stewart Gordon (13/19) Jun 14 2005
• Phoenix (2/18) Jun 15 2005 you can use Python for this feature ;)

Rodolfo Borges <Rodolfo_member pathlink.com> writes:

http://www.digitalmars.com/d/statement.html#foreach

says:
ForeachStatement:
foreach (ForeachTypeList; Expression) Statement

//shouldn't it allow:
foreach(int i; [ 1, 2, 3, 4 ]) {
}

//not pretty to force me write:
static int[] dummy = [ 1, 2, 3, 4 ];
foreach(int i; dummy) {
}

"Ben Hinkle" <ben.hinkle gmail.com> writes:

"Rodolfo Borges" <Rodolfo_member pathlink.com> wrote in message 
news:d8mi9d$v48$1 digitaldaemon.com...
 http://www.digitalmars.com/d/statement.html#foreach

 says:
 ForeachStatement:
 foreach (ForeachTypeList; Expression) Statement

 //shouldn't it allow:
 foreach(int i; [ 1, 2, 3, 4 ]) {
 }

 //not pretty to force me write:
 static int[] dummy = [ 1, 2, 3, 4 ];
 foreach(int i; dummy) {
 }

The issue is that [1,2,3,4] isn't parsed as an expression returning a 
constant static array. One challenge with changing D to support inline 
arrays like that is determining the type of the contents. There have been 
posts in the past that show how to write a varargs function to construct a 
dynamic array at runtime. Here's a variation on those functions that uses 
the new typesafe varargs style:

// Packages inputs into a dynamic array
// pronounced tuh-dah accompanied by a sweeping gesture
template toda(T) {
  T[] toda(T[] x...) {
    return x.dup;
  }
}
// example
import std.stdio;
int main() {
  foreach(int n; toda!(int)(1,2,3,4)) {
    writefln(n);
  }
  return 0;
}

"Uwe Salomon" <post uwesalomon.de> writes:

Perhaps you should add that this is a very cumbersome and slow approach.  
Do not try this at home! :)

Ciao
uwe

"Ben Hinkle" <ben.hinkle gmail.com> writes:

"Uwe Salomon" <post uwesalomon.de> wrote in message 
news:op.ssc2fc1e6yjbe6 sandmann.maerchenwald.net...
 Perhaps you should add that this is a very cumbersome and slow approach. 
 Do not try this at home! :)

why not? Do you mean that it allocates memory every time you call toda? What 
approach do you suggest?

"Uwe Salomon" <post uwesalomon.de> writes:

On Tue, 14 Jun 2005 15:18:57 +0200, Ben Hinkle <ben.hinkle gmail.com>  
wrote:

 "Uwe Salomon" <post uwesalomon.de> wrote in message
 news:op.ssc2fc1e6yjbe6 sandmann.maerchenwald.net...
 Perhaps you should add that this is a very cumbersome and slow approach.
 Do not try this at home! :)

 why not? Do you mean that it allocates memory every time you call toda?  
 What approach do you suggest?

Yes, that's exactly what i mean. I would suggest that:

for (size_t i = 1; i <= 4; ++i)

If you need some more complex array:

static size_t[4] indizes = [9, 23, 1, 7];
//...
foreach (size_t i; indizes)

But i have never needed something like that in my code. More likely is a  
dynamic array (“dynamic” means its contents, not necessarily its size),  
which can be traversed with the same foreach.

Ciao
uwe

"Ben Hinkle" <bhinkle mathworks.com> writes:

"Uwe Salomon" <post uwesalomon.de> wrote in message 
news:op.ssc6gwup6yjbe6 sandmann.maerchenwald.net...
 On Tue, 14 Jun 2005 15:18:57 +0200, Ben Hinkle <ben.hinkle gmail.com> 
 wrote:

 "Uwe Salomon" <post uwesalomon.de> wrote in message
 news:op.ssc2fc1e6yjbe6 sandmann.maerchenwald.net...
 Perhaps you should add that this is a very cumbersome and slow approach.
 Do not try this at home! :)

 why not? Do you mean that it allocates memory every time you call toda? 
 What approach do you suggest?

 Yes, that's exactly what i mean. I would suggest that:

 for (size_t i = 1; i <= 4; ++i)

 If you need some more complex array:

 static size_t[4] indizes = [9, 23, 1, 7];
 //...
 foreach (size_t i; indizes)

I assumed the OP knew about for loops and they explicitly said they knew 
about the static array solution. I was giving an update to an old request 
about being able to construct arrays on-the-fly.

 But i have never needed something like that in my code. More likely is a 
 dynamic array ("dynamic" means its contents, not necessarily its size), 
 which can be traversed with the same foreach.

You can change the content of static arrays, too. I've always interpretted 
the "dynamic" in dynamic arrays to mean the length is only known at run-time 
(ie - dynamically). 

"Uwe Salomon" <post uwesalomon.de> writes:

 You can change the content of static arrays, too. I've always  
 interpretted
 the "dynamic" in dynamic arrays to mean the length is only known at  
 run-time (ie - dynamically).

You're right, of course. I forgot about that.

Ciao
uwe

pragma <pragma_member pathlink.com> writes:

In article <d8mjg5$vuo$1 digitaldaemon.com>, Ben Hinkle says...
Here's a variation on those functions that uses 
the new typesafe varargs style:

// Packages inputs into a dynamic array
// pronounced tuh-dah accompanied by a sweeping gesture
template toda(T) {
  T[] toda(T[] x...) {
    return x.dup;
  }
}

Ben, just a thought: are you 100% certain that you *must* dup the array?

- EricAnderton at yahoo

"Ben Hinkle" <bhinkle mathworks.com> writes:

"pragma" <pragma_member pathlink.com> wrote in message 
news:d8mnnc$13f2$1 digitaldaemon.com...
 In article <d8mjg5$vuo$1 digitaldaemon.com>, Ben Hinkle says...
Here's a variation on those functions that uses
the new typesafe varargs style:

// Packages inputs into a dynamic array
// pronounced tuh-dah accompanied by a sweeping gesture
template toda(T) {
  T[] toda(T[] x...) {
    return x.dup;
  }
}

 Ben, just a thought: are you 100% certain that you *must* dup the array?

 - EricAnderton at yahoo

From http://www.digitalmars.com/d/function.html#variadic it says it is an 
error to refer to the array after the variadic function has returned since 
the array might be constructed on the function's stack space. 

Stewart Gordon <smjg_1998 yahoo.com> writes:

Ben Hinkle wrote:
 "Rodolfo Borges" <Rodolfo_member pathlink.com> wrote in message 

<snip>
//shouldn't it allow:
foreach(int i; [ 1, 2, 3, 4 ]) {


<snip>
 The issue is that [1,2,3,4] isn't parsed as an expression returning a 
 constant static array. One challenge with changing D to support inline 
 arrays like that is determining the type of the contents.

<snip>

This isn't a request for array literals.  It's a request to allow this 
bit of a ForeachStatement to be an array initialiser.  Which suffers 
from this "challenge" to exactly the same extent as

     static int[] dummy = [ 1, 2, 3, 4 ];

does.

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on 
the 'group where everyone may benefit.

Phoenix <phoenix flareware.cz> writes:

Rodolfo Borges napsal(a):
 http://www.digitalmars.com/d/statement.html#foreach
 
 says:
 ForeachStatement:
 foreach (ForeachTypeList; Expression) Statement
 
 //shouldn't it allow:
 foreach(int i; [ 1, 2, 3, 4 ]) {
 }
 
 //not pretty to force me write:
 static int[] dummy = [ 1, 2, 3, 4 ];
 foreach(int i; dummy) {
 }
 
 

you can use Python for this feature ;)