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5400 discussions

us_Timer in TimeStamp
by Thomas_Tan＠fc.choate.edu 26 Oct '97

26 Oct '97

Are you guys going to implement us_Timer field of TimeStamps soon? I need a seed for a random function and this seems to be the best way to go. ------------------------------------------------------ This message sent using the FirstClass SMTP/NNTP Gateway. From: Choate Rosemary Hall 333 Christian St. Wallingford, CT. 06492

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Re: EFLIB strategy and encouragement
by Peter Gerwinski 26 Oct '97

26 Oct '97

Hi, Johan; hi, everybody! According to Johan Larsson: > > EFLIB is licensed under a GNU compatible license which is not ready. Didn't you write in your last mail that you want to charge for commercial use of EFLIB? If so, the license would *not* be GNU compatible because it is an essential component of the GNU GPL and the GNU LGPL that there is no distinction between commercial and non-commercial use of a program or a library. Peter Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer peter.gerwinski(a)uni-essen.de - http://home.pages.de/~peter.gerwinski/ [971005] maintainer GNU Pascal [971001] - http://home.pages.de/~gnu-pascal/ [971005]

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EFLIB strategy and encouragement
by Johan Larsson 26 Oct '97

26 Oct '97

* The EFLIB project have changed strategy: we now aim to establish a standard template library for every Pascal programmer. Hello all, * Introduction EFLIB is a free object-oriented library aiming to become an open standard for all Pascal programming languages. EFLIB includes data structures packaged in classic ADT's, data streams, filtering and conversion, text processing, mathematics (including matrices, complex numbers and vectors). A cross-platform GUI is planned for EFLIB. EFLIB is licensed under a GNU compatible license which is not ready. Therefore, the source code is not released to the public at this time. * Try it You can go to http://ftp.sunet.se/EFLIB/ to download EFLIB or read any of the on-line material. * Get involved We'd love to see you getting involved in the EFLIB project! EFLIB need help from expert programmers on any Pascal platform such as FPK Pascal, GNU Pascal or Borland Delphi. The prototyping language is Borland Pascal, but efforts are made to make the source code very independent of the PL dialect. * More information Check out the Home of EFLIB, especially the on-line documentations and the specification PostScript documents at http://ftp.sunet.se/EFLIB/Manual/Documents/Specifications/. * Mailing lists You can subscribe to any of the EFLIB mailing lists (eflib-users(a)ts.umu.se, eflib-developers(a)ts.umu.se). Read the how-to at http://ftp.sunet.se/EFLIB/Lists/. * Response If you decide to get involved in the free GNU-licensed Pascal standard known as EFLIB, you are encouraged to write an e-mail to EFLIB(a)ts.umu.se or jola(a)ts.umu.se and give a some brief information about yourself. We'll discuss the details with you. Best Regards, Johan Larsson EFLIB Project Manager http://www.ts.umu.se/~jola/ jola(a)ts.umu.se

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Re: Objects question
by Peter Gerwinski 25 Oct '97

25 Oct '97

According to Thomas Tan: > When I took a look at objects.pas in the \test\borland_\ directory (a copy > below), a few questions raise to mind. > [...] > Program Objects;(* Bug fixed: objects only worked in units, not in programs. > *)Type ParentPtr = ^ParentObj; ChildPtr = ^ChildObj;ParentObj = object > Constructor Init; Destructor Fini; Procedure O; c: Char; [...] To me, too. Either your mailer's text editor or your "FirstClass SMTP/NNTP GateWay" or something else has eaten up all line breaks in the source. Or is this just a joke? > 1. Does the character c have to be desposed in the destructor? Of course, not. Only *pointer* variables have to be disposed in the destructor. This is the same with GPC as with BP. > If so, is char > (0) a null character? It is, although this has nothing to do with `Dispose'. > 2. If there are variables (character, arrays ,strings, etc) in a function in > an object, do they have to be manually deleted? Only if they are pointers. > If so, how would I erase each one of them? A modified version of the `objects.pas' test program follows below. Please note that this is a test program which has the only purpose of testing whether the OOP mechanisms in GPC work correctly. For demo programs you can see section "OOP" in the GPC Texinfo online documentation (`info -f gpc -n OOP'). It's not too detailed, but it documents how GPC's OOP differs from that of BP. Since these differences are rather small, any book about "OOP with BP" can help you with GPC, too. > 3. Is there such a thing as a pointer to a function? Yes: Type ProcPtr = ^Procedure; FuncPtr = ^Function ( x: Real ): Real; If you omit the `^', you have BP's "procedural variables" which work in GPC, too. (* Here and in my other mails, I am referring to recent beta versions of GPC, not to the hopelessly outdated gpc-2.0 from December 1996. ;*) Hope this helps, Peter Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer peter.gerwinski(a)uni-essen.de - http://home.pages.de/~peter.gerwinski/ [971005] maintainer GNU Pascal [971001] - http://home.pages.de/~gnu-pascal/ [971005] 8< -------------------------------------------------------------------------- Program Objects; Type StringPtr = ^String; ParentPtr = ^ParentObj; ChildPtr = ^ChildObj; ParentObj = object S: StringPtr; Constructor Init ( Const SomeString: String ); Destructor Fini; Procedure O; c: Char; (* GNU extension: mixing of fields and methods *) Procedure K; virtual; end (* ParentObj *); ChildObj = object ( ParentObj ) Procedure O; Procedure K; virtual; end (* ChildObj *); Var MyObject: ParentPtr; Constructor ParentObj.Init ( Const SomeString: String ); begin (* ParentObj.Init *) New ( S, length ( SomeString ) ); S^:= SomeString; c:= 'K'; end (* ParentObj.Init *); Destructor ParentObj.Fini; begin (* ParentObj.Fini *) Dispose ( S ); end (* ParentObj.Fini *); Procedure ParentObj.O; begin (* ParentObj.O *) write ( 'O' ); end (* ParentObj.O *); Procedure ParentObj.K; begin (* ParentObj.K *) write ( 'y' ); end (* ParentObj.K *); Procedure ChildObj.O; begin (* ChildObj.O *) write ( 'x' ); end (* ChildObj.O *); Procedure ChildObj.K; begin (* ChildObj.K *) inherited K; writeln ( chr ( 8 ) + c ); end (* ChildObj.K *); begin MyObject:= New ( ChildPtr, Init ( 'Hello, world!' ) ); with MyObject^ do begin O; K; writeln ( S^ ); end (* with *); Dispose ( MyObject, Fini ); end. (* The output should be: *) (* OK *) (* Hello, world! *)

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Re: Questing on String
by Peter Gerwinski 25 Oct '97

25 Oct '97

Hello, Thomas; hello, everybody! According to Thomas Tan: > > How does writeln(astring) work, I am not sure whether I understand your question ... To use `writeln', just do writeln ( MyIntegerValue : 6, MyRealValue : 10 : 4, MyStringValue : 7 ); to get 42 3.1415 Hallo! or writeln ( 'Answer = ', MyIntegerValue ); to get Answer = 42 If you want to know how `writeln' works internally, please look at the GPC source, file `rts.c', and in the subdirectory `rts' at the files `rts-write.c' and `rts-wrtinc.c'. If you have more questions about that, please post them on this list. > is the string null terminating? No, but GPC has an additional string type `CString' (or `PChar' for BP compatibility) which *is* null-terminated. If you have, for example, a null-terminated string you want to pass to an external function that wants to have such a string as a parameter (this holds for many external functions written in C), you can use `CString' as follows: Program Environment; (*$X+*) (* Enable "extended syntax" if you want to use `CString' *) Function SetEnv ( Name, Value: CString; overwrite: Integer ): Integer; C; Function GetEnv ( Name: CString ): CString; C; Var S: CString; begin SetEnv ( 'TEST_ENV', 'OK', 1 ); S:= GetEnv ( 'TEST_ENV' ); writeln ( S ); end. > If so, what is the character of null? Not too surprisingly, it is `chr ( 0 )' or `#0'. :-) For `CString'. GPC's native `String' is *not* null-terminated. And to answer your implicit question about GPC string internals: GPC's native `String' is a special case of a "schema type". It looks like a record internally: Type String ( n: Integer ) = record Capacity, length: Integer; (* 8 bytes *) data: packed array [ 1..n ] of Char; (* n bytes *) end (* String *); (* Remark: The above is a perfectly valid type declaration in GNU Pascal or any other compiler that supports Extended Pascal's schema types. It is, however, not identically the same as GPC's `String' since the built-in string functions only work on the built-in string type, but it has the same structure in memory. *) When you declare a string variable with "Var Foo: String ( 42 )" (* Now you see where the round parentheses come from. ;*), the "record field" `Capacity' gets the value 42 assigned, while `length' and `data' remain undefined until you assign a value to the string. You can access a string's capacity with `Foo.capacity' just like a record field. For dynamical allocation of strings, you can define "Type StringPtr = ^String" *without* a specified capacity and then give it when `New'ing the variable. Program Test; Type StringPtr = ^String; Var Foo: StringPtr; begin New ( Foo, 1042 ); (* allocate a String of maximum length 1042 *) Foo^:= 'Hello, world!'; writeln ( Foo^.Capacity ); (* yields "1024" *) writeln ( Foo^ ); (* yields "Hello, world!" *) Dispose ( Foo ); end. In addition to these features of Extended Pascal, GPC supports the following extensions: Type StringPtr = ^String; Var Foo: StringPtr; Foo:= @'Hello, world!'; (* let `Foo' point to a string constant *) Foo:= New ( StringPtr, 42 ); (* let `New' act as a function *) If you want to contribute to the GNU Pascal project, feel free to improve the existing documentation by adding the things I wrote above (and more;-). If you do so, please do not forget to post to this list what you are doing so you can coordinate with others who are currently working on the same field. Hope this helps, Peter Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer peter.gerwinski(a)uni-essen.de - http://home.pages.de/~peter.gerwinski/ [971005] maintainer GNU Pascal [971001] - http://home.pages.de/~gnu-pascal/ [971005]

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Objects question
by Thomas_Tan＠fc.choate.edu 25 Oct '97

25 Oct '97

When I took a look at objects.pas in the \test\borland_\ directory (a copy below), a few questions raise to mind. 1. Does the character c have to be desposed in the destructor? If so, is char (0) a null character? 2. If there are variables (character, arrays ,strings, etc) in a function in an object, do they have to be manually deleted? If so, how would I erase each one of them? 3. Is there such a thing as a pointer to a function? Thanks Tom Program Objects;(* Bug fixed: objects only worked in units, not in programs. *)Type ParentPtr = ^ParentObj; ChildPtr = ^ChildObj;ParentObj = object Constructor Init; Destructor Fini; Procedure O; c: Char; (* GNU extension: mixing of fields and methods *) Procedure K; virtual;end (* ParentObj *);ChildObj = object ( ParentObj ) (* Bug fixed: no dummy variable needed here. *) Procedure O; Procedure K; virtual;end (* ChildObj *);Var MyObject: ParentPtr;Constructor ParentObj.Init;begin (* ParentObj.Init *) c:= 'K';end (* ParentObj.Init *);Destructor ParentObj.Fini;begin (* ParentObj.Fini *) c:= chr ( 0 );end (* ParentObj.Fini *);Procedure ParentObj.O;begin (* ParentObj.O *) write ( 'O' );end (* ParentObj.O *);Procedure ParentObj.K;begin (* ParentObj.K *) write ( 'y' );end (* ParentObj.K *);Procedure ChildObj.O;begin (* ChildObj.O *) write ( 'x' );end (* ChildObj.O *);Procedure ChildObj.K;begin (* ChildObj.K *) inherited K; writeln ( chr ( 8 ) + c );end (* ChildObj.K *);begin MyObject:= New ( ChildPtr, Init ); with MyObject^ do begin O; K; end (* with *); Dispose ( MyObject, Fini );end. ------------------------------------------------------ This message sent using the FirstClass SMTP/NNTP Gateway. From: Choate Rosemary Hall 333 Christian St. Wallingford, CT. 06492

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Questing on String
by Thomas_Tan＠fc.choate.edu 24 Oct '97

24 Oct '97

How does writeln(astring) work, is the string null terminating? If so, what is the character of null? ------------------------------------------------------ This message sent using the FirstClass SMTP/NNTP Gateway. From: Choate Rosemary Hall 333 Christian St. Wallingford, CT. 06492

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Re: GPC question
by Jesper Lund 24 Oct '97

24 Oct '97

Tom: >Thank you again. Is there a list of all the built-in functions somewhere(as well >as all the interfaces)? One more thing, I cannot pass a string[255] variable to >a function or return a string[255] from a function. Is this a bug? >Thanks again. >Tom > First of all: please post general questions about GPC to the GPC list <gpc(a)hut.fi>, and not to me directly. GPC is under development, and so is the documentation. Therefore, AFAIK, there is no *complete* list of the built-in functions. However, GPC is reasonably compatible with Borland Pascal, and the degree of compatibility is increasing day by day, as new versions are released. BTW, do you use the last beta release, dates Oct 1, 1997? If not, get it from the GPC homepage. Regarding your second question, I think you need to define a string type, like type str255 = string [255]; function Foo : str255; begin Foo = 'Foo'; end; This should work. Note that 'string' has a different meaning in GPC than in Borland Pascal. To avoid unexpected effects, use strings of fixed size, such as my str255 -- or study the GPC documentation about "variable length strings". Best wishes, Jesper Lund

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GPC question
by Thomas_Tan＠fc.choate.edu 24 Oct '97

24 Oct '97

Hi, I am looking for a function which returns the current time or date, is there one built in, if so, what do I put after the USES? Tom ------------------------------------------------------ This message sent using the FirstClass SMTP/NNTP Gateway. From: Choate Rosemary Hall 333 Christian St. Wallingford, CT. 06492

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Bug report
by The African Chief 24 Oct '97

24 Oct '97

Hi all, I have found a bug in the new beta. If you export a function in one unit, and then in another unit that uses that first unit, you have the same function (but only in the implementation section), you get a compiler error. This result; [----] two.pas:9: warning: static declaration for `Positive' follows non-static two.pas: In function `Positive': two.pas:10: undeclared identifier `I' (first use this function) two.pas:10: (Each undeclared identifier is reported only once two.pas:10: for each function it appears in.) [----] is produced by these two units; unit one; interface function positive(var i:integer):boolean; implementation function positive(var i:integer):boolean; begin positive := i > 0; end; end. {//} unit two; interface uses one; function negative(var i:integer):boolean; function neutral(var i:integer):boolean; implementation function positive(var i:integer):boolean; begin positive := i > 0; end; function neutral(var i:integer):boolean; begin neutral := i = 0; end; function negative(var i:integer):boolean; begin negative := i < 0; end; end. {////} Best regards, The Chief -------- Dr. Abimbola A. Olowofoyeku (The African Chief) Email: laa12(a)keele.ac.uk Author of: Chief's Installer Pro 4.01 for Win16 and Win32: Winner of PC PLUS Magazine Gold Award (April 1995 U.K. edition) http://ourworld.compuserve.com/homepages/African_Chief/ ftp://ftp.demon.co.uk/pub/ibmpc/win3/apps/chief/pro/chief401.zip

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