Re: [fpc-pascal] Coercing record fields together
On 7/9/2018 9:22 AM, Ryan Joseph wrote: Could I do some RTL magic on a record to loop over its fields and set them to another record by name? In the example below I want to set all the fields in TRecA to matching named fields in TRecB. Just curious if we can do this automatically using RTL. type TRecA = record a: string; b: string; end; type TRecB = record a: string; b: string; c: integer; d: integer; end; for field in recA.GetFields do recB.GetFieldByName(field.name).value := field.value If you make sure that any variable of tRecB is declared first, you can use Var RecB : tRecB; RecA : tRedA ABSOLUTE RecB; Quite obviously, it doesn't work the other way around as tRecB is larger than tRecA... Ralf --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Loss of precision when using math.Max()
Zitat von Florian Klaempfl : I am happy to implement this in delphi mode, but it requires some documentation references how delphi evaluates such expressions (which precision is used when and why) and how they are handled in expressions. These links may be of interest: http://docwiki.embarcadero.com/RADStudio/Tokyo/en/About_Floating-Point_Arithmetic#Understand_the_Data_Flow and http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Floating_point_precision_control_%28Delphi_for_x64%29 ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Coercing record fields together
> On Jul 9, 2018, at 11:57 AM, gabor wrote: > > Hi. > Probably can be done with RTTI (1), enumerators (2) and generics (3) together. > > 1. https://stackoverflow.com/questions/27803383/fpc-rtti-on-records > 2. http://wiki.freepascal.org/for-in_loop#Traversing_container > 3. http://wiki.freepascal.org/Generics > > Michał. Thanks for the tips but ouch that looks complicated, maybe more trouble than it’s worth. Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Loss of precision when using math.Max()
Am 09.07.2018 um 19:55 schrieb g...@wolfgang-ehrhardt.de: Zitat von Martok : To make sure this works, one has to manually make the const expression be of the type required: const e: Extended = Extended(1.0) / 3.0; I seem to remember that this was once documented somewhere for Delphi. Can't seem to find it though, so maybe it was a 3rd-party book? There is no hint of it in the FPC documentation, anyway. As already noted, it is not necessary in Delphi D:\Work\TMP>D:\DMX\M18\DCC32 -b exttest.dpr Embarcadero Delphi for Win32 compiler version 25.0 Copyright (c) 1983,2013 Embarcadero Technologies, Inc. exttest.dpr(14) 15 lines, 0.00 seconds, 20816 bytes code, 13864 bytes data. D:\Work\TMP>exttest 0.333433 0.333433 0. 0. 0. 0. And with Delphi Tokio 10.2.3 Starter G:\TMP>bds -b exttest.dpr G:\TMP>exttest.exe 0.333433 0.333433 0. 0. 0. 0. I am happy to implement this in delphi mode, but it requires some documentation references how delphi evaluates such expressions (which precision is used when and why) and how they are handled in expressions. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Coercing record fields together
Hi. Probably can be done with RTTI (1), enumerators (2) and generics (3) together. 1. https://stackoverflow.com/questions/27803383/fpc-rtti-on-records 2. http://wiki.freepascal.org/for-in_loop#Traversing_container 3. http://wiki.freepascal.org/Generics Michał. W dniu 2018-07-09 o 18:22, Ryan Joseph pisze: Could I do some RTL magic on a record to loop over its fields and set them to another record by name? In the example below I want to set all the fields in TRecA to matching named fields in TRecB. Just curious if we can do this automatically using RTL. type TRecA = record a: string; b: string; end; type TRecB = record a: string; b: string; c: integer; d: integer; end; for field in recA.GetFields do recB.GetFieldByName(field.name).value := field.value Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Loss of precision when using math.Max()
Zitat von Martok :
To make sure this works, one has to manually make the const
expression be of the
type required:
const
e: Extended = Extended(1.0) / 3.0;
I seem to remember that this was once documented somewhere for Delphi. Can't
seem to find it though, so maybe it was a 3rd-party book? There is
no hint of it
in the FPC documentation, anyway.
As already noted, it is not necessary in Delphi
D:\Work\TMP>D:\DMX\M18\DCC32 -b exttest.dpr
Embarcadero Delphi for Win32 compiler version 25.0
Copyright (c) 1983,2013 Embarcadero Technologies, Inc.
exttest.dpr(14)
15 lines, 0.00 seconds, 20816 bytes code, 13864 bytes data.
D:\Work\TMP>exttest
0.333433 0.333433
0.0.
0.0.
And with Delphi Tokio 10.2.3 Starter
G:\TMP>bds -b exttest.dpr
G:\TMP>exttest.exe
0.333433 0.333433
0.0.
0.0.
And I also wrote that the explicit type cast can only be used with
very new Delphi, e.g. compiler version 25 gives for
{$apptype console}
const
x1: extended = extended(1.0)/3.0;
begin
writeln(x1:30:16);
end.
D:\Work\TMP>b18 exttest2.dpr
D:\Work\TMP>D:\DMX\M18\DCC32 -b exttest2.dpr
Embarcadero Delphi for Win32 compiler version 25.0
Copyright (c) 1983,2013 Embarcadero Technologies, Inc.
exttest2.dpr(3) Error: E2089 Invalid typecast
exttest2.dpr(7)
Tokyo compiles without error, I do know now which was the
first version which allows the type cast.
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Re: [fpc-pascal] Coercing record fields together
Just because someone is bound to suggest it, might as well be me. type TRecA = record a: string; b: string; end; type TRecB = record A: TRecA; c: integer; d: integer; end; RecB.A := RecA; Jeff On Mon, Jul 9, 2018, 12:23 PM Ryan Joseph wrote: > Could I do some RTL magic on a record to loop over its fields and set them > to another record by name? In the example below I want to set all the > fields in TRecA to matching named fields in TRecB. Just curious if we can > do this automatically using RTL. > > type > TRecA = record > a: string; > b: string; > end; > > type > TRecB = record > a: string; > b: string; > c: integer; > d: integer; > end; > > > for field in recA.GetFields do > recB.GetFieldByName(field.name).value := field.value > > > Regards, > Ryan Joseph > > ___ > fpc-pascal maillist - fpc-pascal@lists.freepascal.org > http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
[fpc-pascal] How to use Google Protocol Buffer
To connect to a server, I need to use Google's Protocol Buffer format. The only workable parser to convert the protocol definition file to pascal reader/writer source code is: the ProtoBufCodeGen in https://github.com/fundamentalslib/fundamentals5/releases Still, there is no documentation on how to call the generated codes. For example, it generated these: procedure RequestRecordInit(var A: TRequestRecord); procedure RequestRecordFinalise(var A: TRequestRecord); function pbEncodeDataRequestRecord(var Buf; const BufSize: Integer; const A: TRequestRecord): Integer; function pbDecodeValueRequestRecord(const Buf; const BufSize: Integer; var Value: TRequestRecord): Integer; function pbEncodeFieldRequestRecord(var Buf; const BufSize: Integer; const FieldNum: Integer; const A: TRequestRecord): Integer; procedure pbDecodeFieldRequestRecord(const Field: TpbProtoBufDecodeField; var Value: TRequestRecord); I could call pbEncodeDataRequestRecord to convert the TRequestRecord to a stream of byte and store in the Buf but there is not a routine to convert it back from a stream of bytes to the TRequestRecord. The only seemingly useful routine pbDecodeValueRequestRecord, when called with the Buf generated by pbEncodeDataRequestRecord will raise exception "Invalid buffer " Any help? Dennis ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
[fpc-pascal] Coercing record fields together
Could I do some RTL magic on a record to loop over its fields and set them to another record by name? In the example below I want to set all the fields in TRecA to matching named fields in TRecB. Just curious if we can do this automatically using RTL. type TRecA = record a: string; b: string; end; type TRecB = record a: string; b: string; c: integer; d: integer; end; for field in recA.GetFields do recB.GetFieldByName(field.name).value := field.value Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Loss of precision when using math.Max()
Am 03.07.2018 um 23:10 schrieb Florian Klämpfl:
>> OK, then two questions remain: Why does is occur/apply only for (newer?)
>> 3.1.1 versions?
> I dug a little bit deeper, the reason is:
> https://bugs.freepascal.org/view.php?id=25121I tried figuring this out,
> sharing what I found here for reference and a workaround.
In the example of 1.0 / 3.0, both numbers are represented exactly in IEEE-754,
so there is no difference caused by this "range-rounding". Typedef passing has
not changed, and the "minimal" types found in the parser at
compiler/pexpr.pas:1711 have not changed for years either.
So the expression is s32real(1.0) / s32real(3.0) {as before}, which then gets
evaluated by taddnode(typ=slashn) at bestreal precision {as before}, and
returned at s32real precision {as before} and "range rounded" to single {this is
new}. It is then stored in a typed const of whatever type was specified {as
before}.
To make sure this works, one has to manually make the const expression be of the
type required:
const
e: Extended = Extended(1.0) / 3.0;
I seem to remember that this was once documented somewhere for Delphi. Can't
seem to find it though, so maybe it was a 3rd-party book? There is no hint of it
in the FPC documentation, anyway.
Regards,
Martok
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