digitalmars.D.learn - How to re-initialise an associative array.

Gary Willoughby (12/12) Nov 06 2013 A simple request but i'm failing hard. How do i re-init an

JR (3/15) Nov 06 2013 Maybe there's a neater way but x = x.init works.
Daniel Davidson (3/15) Nov 06 2013 x.clear();

Gary Willoughby (6/27) Nov 06 2013 I looked at that but apparently it leaves the array in an unsafe

Daniel Davidson (3/8) Nov 06 2013 Wow! Good to know, thanks!
Daniel Davidson (21/25) Nov 06 2013 Is that still the case? The following seems to work just fine.

Gary Willoughby (4/31) Nov 06 2013 I'm not taking the chance and currently using:

Marco Leise (5/8) Nov 07 2013 x = null; is shorter. Just saying ;)

Gary Willoughby (3/9) Nov 08 2013 Does that actually work? I thought you had to assign at least

Dicebot (3/5) Nov 08 2013 For D arrays and AA's .init, null and [] are pretty much the same

H. S. Teoh (21/23) Nov 06 2013 [...]

Maxim Fomin (2/4) Nov 06 2013 Unfortunately it will not take care of calling struct destructors.

H. S. Teoh (7/15) Nov 06 2013 That applies regardless of how you re-initialize the AA, so that's

"Gary Willoughby" <dev nomad.so> writes:

A simple request but i'm failing hard. How do i re-init an 
associative array? This is obviously not the way:

	import std.stdio;

	void main(string[] args)
	{
		int[string] x;

		x["hello"] = 1;
		x["world"] = 2;

		writefln("%s", x);

		x = new int[string];

		writefln("%s", x); // Should be empty.
	}

Nov 06 2013

"JR" <zorael gmail.com> writes:

On Wednesday, 6 November 2013 at 16:15:36 UTC, Gary Willoughby 
wrote:
 A simple request but i'm failing hard. How do i re-init an 
 associative array? This is obviously not the way:

 	import std.stdio;

 	void main(string[] args)
 	{
 		int[string] x;

 		x["hello"] = 1;
 		x["world"] = 2;

 		writefln("%s", x);

 		x = new int[string];

 		writefln("%s", x); // Should be empty.
 	}

Maybe there's a neater way but x = x.init works.

Nov 06 2013

"Daniel Davidson" <nospam spam.com> writes:

On Wednesday, 6 November 2013 at 16:15:36 UTC, Gary Willoughby 
wrote:
 A simple request but i'm failing hard. How do i re-init an 
 associative array? This is obviously not the way:

 	import std.stdio;

 	void main(string[] args)
 	{
 		int[string] x;

 		x["hello"] = 1;
 		x["world"] = 2;

 		writefln("%s", x);

 		x = new int[string];

 		writefln("%s", x); // Should be empty.
 	}

x.clear();

Nov 06 2013

"Gary Willoughby" <dev nomad.so> writes:

On Wednesday, 6 November 2013 at 16:34:13 UTC, Daniel Davidson 
wrote:
 On Wednesday, 6 November 2013 at 16:15:36 UTC, Gary Willoughby 
 wrote:
 A simple request but i'm failing hard. How do i re-init an 
 associative array? This is obviously not the way:

 	import std.stdio;

 	void main(string[] args)
 	{
 		int[string] x;

 		x["hello"] = 1;
 		x["world"] = 2;

 		writefln("%s", x);

 		x = new int[string];

 		writefln("%s", x); // Should be empty.
 	}

 x.clear();

I looked at that but apparently it leaves the array in an unsafe 
state.

Source: 
http://forum.dlang.org/thread/iu3ll6$2d48$1 digitalmars.com

Nov 06 2013

"Daniel Davidson" <nospam spam.com> writes:

On Wednesday, 6 November 2013 at 16:41:19 UTC, Gary Willoughby 
wrote:
 x.clear();

 I looked at that but apparently it leaves the array in an 
 unsafe state.

 Source: 
 http://forum.dlang.org/thread/iu3ll6$2d48$1 digitalmars.com

Wow! Good to know, thanks!

Nov 06 2013

"Daniel Davidson" <nospam spam.com> writes:

On Wednesday, 6 November 2013 at 16:41:19 UTC, Gary Willoughby 
wrote:
 I looked at that but apparently it leaves the array in an 
 unsafe state.

 Source: 
 http://forum.dlang.org/thread/iu3ll6$2d48$1 digitalmars.com

Is that still the case? The following seems to work just fine. 
Maybe Kenji has been working his magic :-)  ?

import std.stdio;

void main() {
   string[string] foo = ["a" : "a", "b" : "B"];
   writeln(foo);
   foo.clear();
   writeln(foo);
   writeln(foo.length);
   foo["x"] = "this is a test";
   writeln(foo);
   writeln(foo.length);
}
-----------------------------------------
["a":"a", "b":"B"]
[]
0
["x":"this is a test"]
1

Nov 06 2013

"Gary Willoughby" <dev nomad.so> writes:

On Wednesday, 6 November 2013 at 16:49:44 UTC, Daniel Davidson 
wrote:
 On Wednesday, 6 November 2013 at 16:41:19 UTC, Gary Willoughby 
 wrote:
 I looked at that but apparently it leaves the array in an 
 unsafe state.

 Source: 
 http://forum.dlang.org/thread/iu3ll6$2d48$1 digitalmars.com

 Is that still the case? The following seems to work just fine. 
 Maybe Kenji has been working his magic :-)  ?

 import std.stdio;

 void main() {
   string[string] foo = ["a" : "a", "b" : "B"];
   writeln(foo);
   foo.clear();
   writeln(foo);
   writeln(foo.length);
   foo["x"] = "this is a test";
   writeln(foo);
   writeln(foo.length);
 }
 -----------------------------------------
 ["a":"a", "b":"B"]
 []
 0
 ["x":"this is a test"]
 1

I'm not taking the chance and currently using:

x = (int[string]).init;

Nov 06 2013

Marco Leise <Marco.Leise gmx.de> writes:

Am Wed, 06 Nov 2013 18:14:54 +0100
schrieb "Gary Willoughby" <dev nomad.so>:

 I'm not taking the chance and currently using:
 
 x = (int[string]).init;

x = null; is shorter. Just saying ;)

-- 
Marco

Nov 07 2013

"Gary Willoughby" <dev nomad.so> writes:

On Thursday, 7 November 2013 at 15:50:05 UTC, Marco Leise wrote:
 Am Wed, 06 Nov 2013 18:14:54 +0100
 schrieb "Gary Willoughby" <dev nomad.so>:

 I'm not taking the chance and currently using:
 
 x = (int[string]).init;

 x = null; is shorter. Just saying ;)

Does that actually work? I thought you had to assign at least 
some value. I'm gonna test this.

Nov 08 2013

"Dicebot" <public dicebot.lv> writes:

On Friday, 8 November 2013 at 09:04:28 UTC, Gary Willoughby wrote:
 Does that actually work? I thought you had to assign at least 
 some value. I'm gonna test this.

For D arrays and AA's .init, null and [] are pretty much the same 
thing.

Nov 08 2013

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Wed, Nov 06, 2013 at 05:15:34PM +0100, Gary Willoughby wrote:
 A simple request but i'm failing hard. How do i re-init an
 associative array?

[...]

Just assign null to it:

	import std.stdio;
	void main() {
		int[string] aa;
		aa["a"] = 1;
		aa["b"] = 2;
		writeln(aa);

		aa = null;
		aa["a"] = 2;
		aa["b"] = 1;
		writeln(aa);
	}

Output:

	["a":1, "b":2]
	["a":2, "b":1]

The GC will take care of cleaning up the old data.


T

-- 
Don't get stuck in a closet---wear yourself out.

Nov 06 2013

"Maxim Fomin" <maxim maxim-fomin.ru> writes:

On Wednesday, 6 November 2013 at 17:49:41 UTC, H. S. Teoh wrote:
 The GC will take care of cleaning up the old data.


 T

Unfortunately it will not take care of calling struct destructors.

Nov 06 2013

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Wed, Nov 06, 2013 at 06:59:53PM +0100, Maxim Fomin wrote:
 On Wednesday, 6 November 2013 at 17:49:41 UTC, H. S. Teoh wrote:
The GC will take care of cleaning up the old data.


T

 
 Unfortunately it will not take care of calling struct destructors.

That applies regardless of how you re-initialize the AA, so that's
nothing to do with this particular problem. Struct dtors are known to
have many issues anyway.


T

-- 
People who are more than casually interested in computers should have at least
some idea of what the underlying hardware is like. Otherwise the programs they
write will be pretty weird. -- D. Knuth

Nov 06 2013

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digitalmars.D.learn - How to re-initialise an associative array.