[fpc-pascal] FPC class syntax was extended to support delphi code
Hello, FPC-Pascal users discussions I want to notify you that fpc trunk has extensions for the class syntax. Class can have now the next sections: 1. 'var' sections to start regular fields declaration. 'var' can be used after other sections and after methods 2. 'class var' sections to start static fields declaration. Fields delcared in the 'class var' section are static fields 3. 'type' sections to declare types local to a class. It is allowed now to declare nested classes too. 4. 'const' section to declare constants local to a class. 5. 'class property' - similar to regular property but works with static fields and methods Some examples: http://wiki.lazarus.freepascal.org/class_extensions_examples Please test and report bugs found. Best regards, Paul Ishenin. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
Are these features available for {$mode delphi} only?
thanks,
dmitry
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[fpc-pascal] Need help to fix a bug
Hello FPC-Pascal, I wish to fix this bug http://bugs.freepascal.org/view.php?id=15460 but I had found serious problems to understand how data is structured in the TBufIndex and descendant classes, specially the TDoubleLinkedBufIndex. Can somebody help me ? From TBufDataset.BuildIndex I think that: PBufRecLinkItem.Next points to next record. PBufRecLinkItem.Prior points to previous record. Maybe PBufRecLinkItem points to the dataset item data ? Which is supossed to be pointed by: (AIndex as TDoubleLinkedBufIndex).FFirstRecBuf (AIndex as TDoubleLinkedBufIndex).FLastRecBuf The first and last item in the dataset ? Also which is the meaning of this line: (AIndex as TDoubleLinkedBufIndex).FLastRecBuf[(AIndex as TDoubleLinkedBufIndex).IndNr].next:=(AIndex as TDoubleLinkedBufIndex).FFirstRecBuf; I'm completly lost in this piece of code, and I really need it as my SQL fetches could take around 1 minute and reorder data is a must. I know I can reissue the query with a different order but this will take around 20 seconds again while doing it in local memory is a breeze. PS: To check changes in FPC I'm launching a complete build (without clean) but this process will take 2 minutes anyway. Is there a faster way to correctly build only the affected package (in this case fcl-db) ? -- Best regards, JoshyFun ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
Thank you for this message! This stuff sounds really cool. In
particular, I have been itching for class constants.
A few questions come to mind:
a. 'var' sections -- I assume that 'var' is optional when declaring
fields that occur first (i.e. directly after "private", "public", etc)
b. What does "strict private" mean, as opposed to private without
strict? (My best guess is that it would be accessible only within the
methods+properties of that class within the unit, as opposed to being
available anywhere in the same unit where the class is declared...???)
c. What is the purpose of a class method? It would seem to me that
methods should do the same thing whether they are class methods or not.
Traditional variables change from instance to instance, but methods do
not vary between instances, as far as I know-- right?
d. What happens with inheritance?
d.1. wrt class constants and class vars-- are there separate "instances"
(for lack of a better word) of these, one instance for each descendant?
Or is the class var/const only stored once for the ancestor that
declares it, and all descendants share that?
d.2. wrt class methods, can they be virtual? (This strikes me as being
closely related to d.1)
I guess an example is in order for d:
type
t_parent = class
private
class var
x : integer;
const
c = 5;
end;
t_child = class (t_parent)
private
const
c = 7; // can I do this?
end;
If I change t_child.x will it change t_parent.x?
e. Is it available in {$mode objfpc}? (I hope I hope I hope)?
I'd love to test this stuff out, though I usually stick with release
versions... perhaps this is what is needed for me to take the plunge!
Either way, I'm looking forward to this being released. Great work.
Cheers,
David
On Wed 13 Jan 2010, Paul Ishenin wrote:
> Hello, FPC-Pascal users discussions
>
> I want to notify you that fpc trunk has extensions for the class
syntax.
>
> Class can have now the next sections:
>
> 1. 'var' sections to start regular fields declaration. 'var' can be
used
> after other sections and after methods
> 2. 'class var' sections to start static fields declaration. Fields
> delcared in the 'class var' section are static fields
> 3. 'type' sections to declare types local to a class. It is allowed
now
> to declare nested classes too.
> 4. 'const' section to declare constants local to a class.
> 5. 'class property' - similar to regular property but works with
static
> fields and methods
>
> Some examples:
> http://wiki.lazarus.freepascal.org/class_extensions_examples
>
> Please test and report bugs found.
>
> Best regards,
> Paul Ishenin.
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> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>
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Re: [fpc-pascal] FPC class syntax was extended to support delphi code
David Emerson wrote: b. What does "strict private" mean, as opposed to private without strict? (My best guess is that it would be accessible only within the methods+properties of that class within the unit, as opposed to being available anywhere in the same unit where the class is declared...???) In Delphi what you have described is exactly what strict private gives you. c. What is the purpose of a class method? It would seem to me that methods should do the same thing whether they are class methods or not. Traditional variables change from instance to instance, but methods do not vary between instances, as far as I know-- right? Class methods allow you to call the method without instantiating the class first. For example, Result := TMyClass.MyClassFunction; -- Doug C. - A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
Doug Chamberlin wrote: > Class methods allow you to call the method without instantiating the > class first. For example, Result := TMyClass.MyClassFunction; Oh, that is so cool! I suppose that probably means that class methods can only reference class variables/methods/properties. Cheers, David ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
David Emerson wrote: Doug Chamberlin wrote: Class methods allow you to call the method without instantiating the class first. For example, Result := TMyClass.MyClassFunction; Oh, that is so cool! I suppose that probably means that class methods can only reference class variables/methods/properties. Yup! Of course, there are pros and cons to all this. Our once simple, straightforward language is not littered with "convenience" features that are not necessary at all. For example, what is the big advantage of class methods over simple functions and procedures? -- Doug C. - A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
>
> Yup!
>
> Of course, there are pros and cons to all this. Our once simple,
> straightforward language is not littered with "convenience" features that
> are not necessary at all. For example, what is the big advantage of class
> methods over simple functions and procedures?
>
Class methods can be virtual and have access to other (perhpas protected)
class members of the class.
type
TA = class
public
class procedure Hello; virtual;
end;
TB = class(TA)
public
class procedure Hello; override;
end;
TAClass = class of TA;
{ TA }
class procedure TA.Hello;
begin
ShowMessage('Hello this is ' + ClassName); // see I can access ClassName
end;
{ TB }
class procedure TB.Hello;
begin
inherited Hello;
ShowMessage('A different message here');
end;
{ TForm1 }
procedure TForm1.Button1Click(Sender: TObject);
var
SomeClass: TAClass;
begin
SomeClass := TB;
SomeClass.Hello;
end;
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Re: [fpc-pascal] FPC class syntax was extended to support delphi code
On Wed, Jan 13, 2010 at 19:13, David Emerson wrote: > > d.2. wrt class methods, can they be virtual? (This strikes me as being > closely related to d.1) > Definitely, yes! (and I believe that was available before class vars/consts) I use this great feature for (de)serialization of messages in my client/server communication: TMessage = class public constructor Create; virtual; class function GetCode: Word; virtual; Code: Word; ... end; constructor TMessage.Create; begin Code := GetCode; end; So, when I want to create new message, I just call TLoginMessage.Create or TChatMessage.Create or whatever (those classes override GetCode, and everything works perfect). ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
RE: [fpc-pascal] FPC class syntax was extended to support delphi code
>-Original Message- >From: fpc-pascal-boun...@lists.freepascal.org >[mailto:fpc-pascal-boun...@lists.freepascal.org] On Behalf Of Doug Chamberlin >Sent: Wednesday, January 13, 2010 11:21 AM >To: FPC-Pascal users discussions >Subject: Re: [fpc-pascal] FPC class syntax was extended to support delphi code > >David Emerson wrote: >> Doug Chamberlin wrote: >>> Class methods allow you to call the method without instantiating the >>> class first. For example, Result := TMyClass.MyClassFunction; >> >> Oh, that is so cool! I suppose that probably means that class methods >> can only reference class variables/methods/properties. > >Yup! > >Of course, there are pros and cons to all this. Our once simple, >straightforward language is not littered with "convenience" features >that are not necessary at all. For example, what is the big advantage of >class methods over simple functions and procedures? Some operations (procedures/functions) just go naturally with Classes but don't belong to any particular instance of that class. An example might be calculating the area of overlap between two geographic polygons (instances of the class) where the function returning the overlap area is a class function rather than an instance function/method of either of the two polygons. Contrived, but imaginable. >-- >Doug C. >- >A: Because it messes up the order in which people normally read text. >Q: Why is top-posting such a bad thing? >A: Top-posting. >Q: What is the most annoying thing in e-mail? >___ >fpc-pascal maillist - fpc-pascal@lists.freepascal.org >http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] [OT] which editor - Vim and Exuberant Ctags?
On Sun, Jan 10, 2010 at 02:44:46PM +0100, Hans-Peter Suter wrote: > I'm on a mac and use TextMate currently. As it doesn't jump between > declaration and implementation and ist mac-only, I am looking for a > replacement. > > Is Emacs a good choice? Does it work well with FPC? I do my Pascal development using GVim and tag files generated with Exuberant Ctags. I am underwhelmed by the support for Pascal as a language relative to ones like the C languages that are tied to the history of the Vi editor family. Exuberant Ctags will generate a tag file for classic Pascal code, but only stand-alone functions and procedures are supported. There is no support for generating tags for variables of any kind. Also, there is not support for object oriented Pascal. This is what I mean by stand-alone functions and procedures. Any use of dot notation with functions or procedures is ignored. Better support for prioritizing IMPLEMENTATION versus INTERFACE sections would also be a plus. Anyone know of any better options for navigating Pascal source code from a classic or general purpose programmer's text editor? Ideal would be a better way of generating tag files. I don't suppose anyone has considered getting Cscope to work with Pascal source code? ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
dmitry boyarintsev wrote:
Are these features available for {$mode delphi} only?
No. For objfpc too.
Best regards,
Paul Ishenin.
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Re: [fpc-pascal] FPC class syntax was extended to support delphi code
Cox, Stuart TRAN:EX wrote: Some operations (procedures/functions) just go naturally with Classes but don't belong to any particular instance of that class. An example might be calculating the area of overlap between two geographic polygons (instances of the class) where the function returning the overlap area is a class function rather than an instance function/method of either of the two polygons. Contrived, but imaginable. Oh, I can imagine such methods also. And I've used them before. I just don't see the big advantage over having them be global functions/procedures located in the same unit as the class they operate on. So, as often as not, I go and create the global functions instead. Never could decide either way to go. -- Doug C. - A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC class syntax was extended to support delphi code
David Emerson wrote:
a. 'var' sections -- I assume that 'var' is optional when declaring
fields that occur first (i.e. directly after "private", "public", etc)
Yes.
b. What does "strict private" mean, as opposed to private without
strict? (My best guess is that it would be accessible only within the
methods+properties of that class within the unit, as opposed to being
available anywhere in the same unit where the class is declared...???)
"strict private" is not a new feature. it means that something is
private for this class only and can't be accessed by other classes or
routines of the unit.
c. What is the purpose of a class method? It would seem to me that
methods should do the same thing whether they are class methods or not.
Traditional variables change from instance to instance, but methods do
not vary between instances, as far as I know-- right?
Class method is not a new feature as well as static class method. Class
method allows you to have methods which belongs to the class instead of
an instance of the class. Class methods can be virtual. Static class
methods can't.
d. What happens with inheritance?
d.1. wrt class constants and class vars-- are there separate "instances"
(for lack of a better word) of these, one instance for each descendant?
Or is the class var/const only stored once for the ancestor that
declares it, and all descendants share that?
Class vars (static class fields) are stored only once for the class
which declares them and all descendants share that.
Example:
TSomeClass = class
class var Value: Integer;
end;
TDescendant = class(TSomeClass);
begin
TSomeClass.Value := 1;
TDescendant.Value := 2;
WriteLn(TSomeClass.Value); // this must output 2
end;
Class static field is not a new feature. But now you can declare them
using 'class var' section after methods or 'type'/'const' section.
d.2. wrt class methods, can they be virtual? (This strikes me as being
closely related to d.1)
class methods can be virtual. static class methods can't.
I guess an example is in order for d:
type
t_parent = class
private
class var
x : integer;
const
c = 5;
end;
t_child = class (t_parent)
private
const
c = 7; // can I do this?
end;
In ObjFpc mode you can't do this because t_child.c duplicates
t_parent.c. In Delphi mode you can do this. I have no personal opinion
how ObjFpc mode should work here but this behavior is consistent with
restrictions for identifier duplication we currently have in objfpc mode.
e. Is it available in {$mode objfpc}? (I hope I hope I hope)?
yes.
Best regards,
Paul Ishenin.
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[fpc-pascal] Swopping two items in TCollection
Hi list I have a class derived from Tcollection, holding items derived from TCollectionItem. How do I swop two items in the collection? FItem is of type TList which has an exchange function, but that is private and not accessable to me. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
