Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
2011/10/25 : >> targethread.queue( >> procedure(targetobject:ttargetobject;a:integer;b:someobject;c:string) >> begin >> targetobject.destinationprocedure(a,b,c); >> end; >> >> Note how common this looks compared to the original. > > One point is that you could do the above with a local (and named) procedure > as well, and still have all the context. At the very least you would not be > raping pascal's readability by putting a > complete procedure declaration inside a code block. How would you preserve the context without finding some place somewhere (on the heap) to store the current values of a, b, and c? The natural alternative to a closure if you don't have them in an OO language is instead of passing a closure you pass an object (this pattern is called Functor). The object contains the function along with some state. Of course in a static language this involves a lot of boiler plate to define the needed classes with their methods (one class definition for every different closure) but once you have done this you can use it like the closure in the above example and its usage is totally readable: targetthread.queue(TMyFunctor.Create(targetobject, a, b, c)); ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
2011/10/25 Marco van de Voort : > Equivalent solution with anon functions: > > targethread.queue( > procedure(targetobject:ttargetobject;a:integer;b:someobject;c:string) > begin > targetobject.destinationprocedure(a,b,c); > end; shouldn't this be targethread.queue( procedure begin targetobject.destinationprocedure(a,b,c); end; without any parameters since all these variables are captured from the current scope into the closure? The other thread should not need to know anything about them to call it. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
In our previous episode, Bernd said: > > Equivalent solution with anon functions: > > > > targethread.queue( > > ? procedure(targetobject:ttargetobject;a:integer;b:someobject;c:string) > > ? ? ? ? ? ? ?begin > > ? ? ? ? ? ? ? ?targetobject.destinationprocedure(a,b,c); > > ? ? ? ? ? ? ?end; > > shouldn't this be > > targethread.queue( > procedure > begin >targetobject.destinationprocedure(a,b,c); > end; > > without any parameters since all these variables are captured from the > current scope into the closure? The other thread should not need to > know anything about them to call it. Afaik you are right. Delphi also allowed the other form, but I thought the syntax would force immediately evaluation of the parameters (and thus only the parameters be stored in case any of a ,b or c are expressions, not all parts of the expressions). But indeed then the other side also has to call it with parameters, and in this example that defeats the purpose. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
05.11.2011 22:42, Bernd пишет: 2011/10/25: targethread.queue( procedure(targetobject:ttargetobject;a:integer;b:someobject;c:string) begin targetobject.destinationprocedure(a,b,c); end; Note how common this looks compared to the original. One point is that you could do the above with a local (and named) procedure as well, and still have all the context. At the very least you would not be raping pascal's readability by putting a complete procedure declaration inside a code block. How would you preserve the context without finding some place somewhere (on the heap) to store the current values of a, b, and c? The natural alternative to a closure if you don't have them in an OO language is instead of passing a closure you pass an object (this pattern is called Functor). The object contains the function along with some state. Of course in a static language this involves a lot of boiler plate to define the needed classes with their methods (one class definition for every different closure) but once you have done this you can use it like the closure in the above example and its usage is totally readable: targetthread.queue(TMyFunctor.Create(targetobject, a, b, c)); ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal But modern trend is to add closures into OO languages, because code become more laconic. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
On Sat, 5 Nov 2011, Bernd wrote: 2011/10/25 : targethread.queue( procedure(targetobject:ttargetobject;a:integer;b:someobject;c:string) begin targetobject.destinationprocedure(a,b,c); end; Note how common this looks compared to the original. One point is that you could do the above with a local (and named) procedure as well, and still have all the context. At the very least you would not be raping pascal's readability by putting a complete procedure declaration inside a code block. How would you preserve the context without finding some place somewhere (on the heap) to store the current values of a, b, and c? Procedure SomeOuter; Var d,e,f : SomeType; Procedure SomeInner(targetobject:ttargetobject;a:integer;b:someobject;c:string) begin targetobject.destinationprocedure(a,b,c); end; begin Targethread.queue(@SomeInner(aobject,d,e,f)); end; No difference with 'closure', except more readable. Michael.___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
06.11.2011 1:46, Michael Van Canneyt пишет: On Sat, 5 Nov 2011, Bernd wrote: 2011/10/25 : targethread.queue( procedure(targetobject:ttargetobject;a:integer;b:someobject;c:string) begin targetobject.destinationprocedure(a,b,c); end; Note how common this looks compared to the original. One point is that you could do the above with a local (and named) procedure as well, and still have all the context. At the very least you would not be raping pascal's readability by putting a complete procedure declaration inside a code block. How would you preserve the context without finding some place somewhere (on the heap) to store the current values of a, b, and c? Procedure SomeOuter; Var d,e,f : SomeType; Procedure SomeInner(targetobject:ttargetobject;a:integer;b:someobject;c:string) begin targetobject.destinationprocedure(a,b,c); end; begin Targethread.queue(@SomeInner(aobject,d,e,f)); end; No difference with 'closure', except more readable. Michael. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal Closures can be returned as a function result but nested procedure not (more strictly, this can be complied but will not work because of lifetime of nested procedure). ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
2011/11/5 Michael Van Canneyt : > Procedure SomeOuter; > > Var > d,e,f : SomeType; > > Procedure > SomeInner(targetobject:ttargetobject;a:integer;b:someobject;c:string) > begin > targetobject.destinationprocedure(a,b,c); > end; > > begin > Targethread.queue(@SomeInner(aobject,d,e,f)); > end; > > No difference with 'closure', except more readable. > > Michael. I doubt that this would even compile. Also As I pointed out already the example was wrong, the procedure does not have any arguments, the closure must be "closed over" these variables. and this: begin Targethread.queue(@SomeInner); end; would compile but it would just pass the procedure variable. This is not a closure. How is the other thread supposed to know the values of the variables that existed only in the scope of SomeOuter? A closure would be something like this: Procedure SomeOuter; Var d,e,f : SomeType; Procedure SomeInner begin targetobject.destinationprocedure(a,b,c); end; begin Targethread.queue(SomeInner); end; The compiler would need to create an object on the heap containing the procedure *along* with the needed variables a,b,c and then pass the entire object. The receiving side could then call this method and it would still have access to these variables. A closure has enclosed variables from the surrounding scope where it was created, hence the name 'closure'. You cannot do this with a procedure variable alone, you need an object on the heap to contain the enclosed variables. The Delphi compiler will behind the scenes create a reference counted object with an 'invoke' method (the procedure SomeInner) and all its needed variables. It is basically a syntactic shortcut to explicitly defining this class, and creating an instance of it. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] Free Pascal 2.6.0rc1 released
Hello, We have placed the first release-candidate of the Free Pascal Compiler version 2.6.0 on our ftp-servers. You can help improve the upcoming 2.6.0 release by downloading and testing this release. If you want you can report what you have done here: http://wiki.freepascal.org/Testers_2.6.0 Changes that may break backwards compatibility are documented at: http://wiki.freepascal.org/User_Changes_2.6.0 Downloads are available at the FTP server at: ftp://freepascal.stack.nl/pub/fpc/beta/2.6.0-rc1/ Enjoy! The Free Pascal Compiler Team Free Pascal Compiler Version 2.6.0rc1 ** What's New in 2.6.0rc1 ** Free Pascal 2.6.0 is a new major version of the Free Pascal compiler. Please also see http://wiki.freepascal.org/User_Changes_2.6.0 for a list of changes that may affect the behaviour of previously working code, and how to cope with these changes. Some highlights are: Platforms: * iPhoneSimulator target Compiler: * Many new language features: * Objective-Pascal dialect, supported on all Mac OS X and iOS targets * constref parameter modifier for "const by reference" * Pascal boolean types with multiple sizes (boolean16/32/64) * ISO 7185 language mode (except for I/O). Features amongst others: * nested procedure variables * non-local goto's * Mac Pascal mode improvements * nested procedure variables * univ modifier * Intrinsics * sar (shift arithmetic right) * bsf/bsr (bitscan forward/reverse) * Delphi compatibility mode improvements * Nested types, class variables and class local constants * Advanced records syntax (no constructors yet) * (for..in) Enumerators in records * Class and record helpers * Generic records, arrays and procedural types * Delphi-compatibility of generics improved * Scoped enumerations * Custom messages for "deprecated" directive * Ability to use "&" for escaping keywords * New ARM code generator features * ARM VFPv2 and VFPv3 floating point unit support * Thumb-2 support Packages: * Many improvements to the rtl * Many improvements to the database units (fcl-db) * Objective-Pascal interfaces to Foundation, AppKit, CoreData and WebCore * OpenGL headers updated to OpenGL 4.0 Details about these new features can be found at http://wiki.freepascal.org/FPC_New_Features_2.6.0 See http://bugs.freepascal.org/changelog_page.php for the list of reported bugs that have been fixed in this release. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Free Pascal 2.6.0rc1 released
On 5/11/2011 20:27, Marco van de Voort wrote: Downloads are available at the FTP server at: ftp://freepascal.stack.nl/pub/fpc/beta/2.6.0-rc1/ Cant download 550 /pub/fpc/beta/2.6.0-rc1/: Permission denied. Luiz ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Free Pascal 2.6.0rc1 released
2011/11/5 Luiz Americo Pereira Camara : > On 5/11/2011 20:27, Marco van de Voort wrote: >> >> Downloads are available at the FTP server at: >> >> ftp://freepascal.stack.nl/pub/fpc/beta/2.6.0-rc1/ > > Cant download > > 550 /pub/fpc/beta/2.6.0-rc1/: Permission denied. > > Luiz x( http://imagebin.org/182703 -- Silvio Clécio === Blog - Twitter - Facebook - LazSolutions - Lazarus-BR - === * Conheça nosso canal IRC sobre Lazarus: #lazarus-br * === ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Free Pascal 2.6.0rc1 released
At 04:47 PM 11/5/2011, Luiz Americo Pereira Camara wrote: On 5/11/2011 20:27, Marco van de Voort wrote: Downloads are available at the FTP server at: ftp://freepascal.stack.nl/pub/fpc/beta/2.6.0-rc1/ Cant download 550 /pub/fpc/beta/2.6.0-rc1/: Permission denied. ditto... :-( Ralf ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Free Pascal 2.6.0rc1 released
06.11.2011 3:47, Luiz Americo Pereira Camara пишет: On 5/11/2011 20:27, Marco van de Voort wrote: Downloads are available at the FTP server at: ftp://freepascal.stack.nl/pub/fpc/beta/2.6.0-rc1/ Cant download 550 /pub/fpc/beta/2.6.0-rc1/: Permission denied. Luiz ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ftp://ftp.freepascal.org/pub/fpc/beta/2.6.0-rc1/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Delphi's anonymous functions in Free Pascal
On Sat, 5 Nov 2011, Bernd wrote: A closure has enclosed variables from the surrounding scope where it was created, hence the name 'closure'. You cannot do this with a procedure variable alone, you need an object on the heap to contain the enclosed variables. The Delphi compiler will behind the scenes create a reference counted object with an 'invoke' method (the procedure SomeInner) and all its needed variables. It is basically a syntactic shortcut to explicitly defining this class, and creating an instance of it. I understand all that. That's not the issue. I didn't mean to say that my example will work with the compiler NOW. Obviously, it would need some extension of the compiler to implement closures. The only thing I am arguing is that the syntax could have been more clear. Definining a function inside code (or as an argument to another function) is just not Pascal; It goes against everything Pascal stands for. You could perfectly explicitly declare the closure function outside the code block it is used in, as long as it is AFTER the variables it would need from the outer scope. That is what I wanted to show with my snippet of code. Probably you'd need some kind of extra keyword to distinguish it from 'normal' nested functions. I am not against closure functionality, although I highly doubt it is *that* useful as some people make it out to be. Even so, I use it in my Javascript programming. But in Pascal, I would like to see it implemented in a way that doesn't go against Pascal philosophy. In that regard, I consider the way that Borland/CodeGear/Embarcadero implemented it a monstrosity. It simply hurts the eyes... Michael. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] Re: Free Pascal 2.6.0rc1 released
> We have placed the first release-candidate of the Free Pascal Compiler > version 2.6.0 on our ftp-servers. Congratulations! That's an impressive list of new features. I've been anticipating this release for some time. A couple of questions: where can this be found in svn? I don't see a tag for it, and fixes_2_6 hasn't been modified for 8 weeks or so. Secondly, will there be additional merges from trunk to fixes_2_6? If I recall the last time I checked the page with the list of potential merges from trunk to fixes_2_6 I believe it was quite long. Particularly I was hoping for revision 19036 (resolving issue 19404, fixing shared library loading and unloading for Linux platforms) to make it into the 2.6 release. Again, congratulations. I'll start using the release candidate next week at work and will report any issues I find. -SG -- This email is fiction. Any resemblance to actual events or persons living or dead is purely coincidental. Seth Grover ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Re: Free Pascal 2.6.0rc1 released
On 06 Nov 2011, at 02:32, Seth Grover wrote: > A couple of questions: where can this be found in svn? I don't see a > tag for it, and fixes_2_6 hasn't been modified for 8 weeks or so. http://svn.freepascal.org/svn/fpc/tags/release_2_6_0_rc1/ Jonas ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] Re: Free Pascal 2.6.0rc1 released
Jonas, thanks for the link. For some reason it wasn't showing up on the viewvcs interface until I cleared my browser cache and refreshed. Thanks again. -SG -- This email is fiction. Any resemblance to actual events or persons living or dead is purely coincidental. Seth Grover ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
