Re: [DUG]: about SET
Yes, I can use an array, but I don't like it here. Actually I use the set as a parameter for passing the values to a function, and most time I need only one or two values to be passed. Only occasionally pass more values. So in most time I have to ignore all other values or giving the dumb values except one or two that I need. The program will look ugly. Don't you think so? During the weekend I wrote a small class (really small) to encapsulate the Upper, Lower and Count of a set... You would need to create a class for each enumeration as it stands and is therefore a perfect example of why I'd like to see templates implemented in pascal... If anyone wants the class and example project (4k zip) personal email me and I'll send it... It's so simple I don't know if it's worth cluttering the delphi FTP... Example: procedure TForm1.CheckBox1Click(Sender: TObject); var I : TEnumElements; begin with Sender as TCheckboc do if Checked then SE.Contents :=SE.Contents+[TEnumElements(Tag)] else SE.Contents :=SE.Contents-[TEnumElements(Tag)]; Caption := ''; for I := SE.Lower to SE.Upper do begin if I in SE.Contents then Caption := Caption + Names[I]+' '; end; end; I'm tempted to implement the set internally as a dynamic array so that NEXT and PRED can be used... and offer a .AsSet property instead on the contents which constructs the set from the array... -- Aaron Scott-Boddendijk Jump Productions (07) 838-3371 Voice (07) 838-3372 Fax --- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz
RE: [DUG]: about SET
Hi, all.
Aaron wrote:
During the weekend I wrote a small class (really small) to encapsulate the
Upper, Lower and Count of a set... You would need to create a
class for each enumeration
as it stands and is therefore a perfect example of why I'd like
to see templates implemented
in pascal... If anyone wants the class and example project (4k
zip) personal email me and
I'll send it... It's so simple I don't know if it's worth
cluttering the delphi FTP...
[snippage]
Hrmm.. I've written an Object Pascal template/macro processor which we use
here at Profax. I have considered offering the processor as a public domain
utility and 'donating' the executable to the Delphi community since
Templates are pretty damn handy for efficient type-safe containers and are
the one thing I actually miss from C++.
Here is a snippet of sample template code to explain the grammar:
-- cut here --
unit tDList;
{
NewLook Doubly Linked List Class Template
Copyright (c) 1997, 1998 NewLook Through Old Windows Limited -
www.newlook.co.nz
}
{
Template Params
ItemType: 'Type of Item' = Pointer;
TypePrefix: 'Type Prefix' = u;
FreeItem(Item): 'Code for FreeItem' = FreeMem(Item);
}
{.DEFINE DEBUG}
interface
uses
Classes;
type
P|TypePrefix|DListNode = ^T|TypePrefix|DListNode;
T|TypePrefix|DListNode = record
Prior: P|TypePrefix|DListNode;
Next: P|TypePrefix|DListNode;
Item: ItemType;
end;
T|TypePrefix|DList = class
private
FOwnsItems: Boolean;
FCount: Integer;
FFirst: P|TypePrefix|DListNode;
FLast: P|TypePrefix|DListNode;
function GetItem(Node: P|TypePrefix|DListNode): ItemType;
procedure SetItem(Node: P|TypePrefix|DListNode; Item: ItemType);
...
function T|TypePrefix|DList.Delete(Node: P|TypePrefix|DListNode):
P|TypePrefix|DListNode;
begin
Assert(Node nil);
Result := Node^.Next;
if Node^.Prior = nil then
FFirst := Node^.Next
else
Node^.Prior^.Next := Node^.Next;
if Node^.Next = nil then
FLast := Node^.Prior
else
Node^.Next^.Prior := Node^.Prior;
if FOwnsItems then
FreeItem(Node^.Item);
Dispose(Node);
Dec(FCount);
{$IFDEF DEBUG}
Invariant;
{$ENDIF}
end;
-- cut here --
Explanation:
The Template Params section is a special comment block which the processor
understands. All macros and template parameters and there default expansions
(if any) are specified here.
The '|' character is the token pasteing operator and merges the various
portions into a single token (or word) e.g. P|TypePrefix|DListNode when
TypePrefix is u would result in the token PuDListNode being specific in the
output unit file.
The Template Processor is a Delphi executable which reads a template
specification unit (.nlt) and prompts for the paramater values and an output
unit name (.pas) which it then produces. The processor is a single pass
lexer/tokenizer/macro processor engine working largely upon memory streams
so it seems pretty quick. It actually depends upon itself now since the code
now uses a uDListstring template internally rather than TStringLists
which gave a nice order of magnitude speed improvement for inserts and
deletes which macro engines by their nature do quite a bit off.
If anyone is interested, I can email them the .EXE and the complete
uDList.nlt as a sample. If lots of people end up asking, I'll put it up on
the 'NewLook Free Stuff' page at http://www.newlook.co.nz/freestuff.htm
instead.
TTFN,
Paul.
---
New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED]
Website: http://www.delphi.org.nz
[DUG]: about SET
Hi all, Does anyone know how to get the number of element in a set and how to know the value stored in first, second .. position of a set easily? I know we can loop through the whole set, but is there any faster way? Thanks, Jim Zheng --- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz
RE: [DUG]: about SET
Jim wrote: I don't think high(setname) works for a set. We maybe confuse 'set' and 'enumerated', don't we? Almost certainly. g cheers, peter == Peter Hyde, SPIS Ltd, Christchurch, New Zealand * TurboNote: http://TurboPress.com/tbnote.htm -- small, FREE and very handy * Print-to-Web automation http://TurboPress.com * Web design, automation and hosting specialists Find all the above and MORE at http://www.spis.co.nz --- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz
RE: [DUG]: about SET
Is there any reason you can't use an array instead? Cheers, Cory Shanks -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Jim Zheng Sent: Friday, 19 February 1999 16:29 To: Multiple recipients of list delphi Subject: RE: [DUG]: about SET So that means, there is not faster way than looping through whole set to check each one from base type appears in the set. But is there any faster way to know the count of a set, or looping is the only way? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Cooke, Andrew Sent: Friday, 19 February 1999 16:13 To: Multiple recipients of list delphi Subject: RE: [DUG]: about SET However, you can declare a set as: type TMyset = set of TMytype; and High() will work for TMyType. The help explicitly states that order has no meaning in a set, so you cannot find out the order of the elements in a set - you can only iterate through the elements of the base type and see if they appear in the set. Andrew. -Original Message- From: Peter Hyde [SMTP:[EMAIL PROTECTED]] Sent: Saturday, February 20, 1999 5:09 AM To: Multiple recipients of list delphi Subject:RE: [DUG]: about SET Jim wrote: I don't think high(setname) works for a set. We maybe confuse 'set' and 'enumerated', don't we? Almost certainly. g cheers, peter == Peter Hyde, SPIS Ltd, Christchurch, New Zealand * TurboNote: http://TurboPress.com/tbnote.htm -- small, FREE and very handy * Print-to-Web automation http://TurboPress.com * Web design, automation and hosting specialists Find all the above and MORE at http://www.spis.co.nz -- - New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz -- - New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz -- - New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz --- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz
