Re: [fpc-pascal] const parameter writeable
On Mon, May 01, 2006 at 12:07:55PM -0600, L505 [EMAIL PROTECTED] wrote: Only the pointer itself is the parameter and read-only. Where the pointer points to is irrelevant. I remember this from using classes where you can still access the class properties - should have thought about that before posing the question :). But in this case I'm wondering why you want to give a pointer instead of the real type? did you mean this ? : procedure ChangeRec1(const Rec: TSomeRec); begin Rec.a:= 'string A'; end; Yes. Because I can't pass a PSomeRec to that function, only a TSomeRec Where is the problem? If you allocated the memory by new() as in your example you could call ChangeRec1(RecPtr^); and the compile (hopefully) uses the pointer. But in this case you will get an compiler error because you can't change a constant value. It seemed that I didn't get the point from your original mail: Name the procedure CHANGERec1 and change a value but declare the parameter as constant. Otherwise, I don't know what you mean.. Now _I_'m a little bit confused. Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] Constant object
How can I declare a constant object? var MyTest: TObject; begin MyTest := TObject.Create; end. works (for sure). How can I declare 'const'? Thanks Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] const parameter writeable
But in this case I'm wondering why you want to give a pointer instead
of the real type?
did you mean this ? :
procedure ChangeRec1(const Rec: TSomeRec);
begin
Rec.a:= 'string A';
end;
Yes.
Well, this is a Precord. That doesn't work. That is why I was confused.
Because I can't pass a PSomeRec to that function, only a TSomeRec
Where is the problem? If you allocated the memory by new() as in your
example you could call
ChangeRec1(RecPtr^);
and the compile (hopefully) uses the pointer.
Yes, but you are repeating what Jonas says - if you would have told me this
first, you
would have gotten the brownie points. But Jonas gets them. :-)
But in this case you will get an compiler error because you can't
change a constant value.
It seemed that I didn't get the point from your original mail:
Name the procedure CHANGERec1 and change a value but declare the
parameter as constant.
I was asking why I could write to a const. But in fact I was not writing to the
CONST, I
was actually writing to the const data it pointed to. With SomeRec^ I cannot
write to
const. Problem solved.
I was using sloppy Delphi style code without ^ since Delphi enforces this
sloppy style of
coding, and now I know why not to use sloppy delphi style code.
What I was confused about was why you recommended TSomeRec when we are dealing
with
PSomeRec.
I also stated that I knew you can pass TSomeClass as a const, you can still
access it's
properties even though it is a const.
program project1;
{$mode objfpc}{$H+}
type
TSomeClass = class
a: string;
b: string;
end;
procedure ChangeClass(const SomeClass: TSomeClass);
begin
SomeClass.a:= 'string A';
end;
var
SomeClass: TSomeClass;
begin
someclass:= TSomeClass.create;
ChangeClass(someclass);
writeln(someclass.a);
someclass.free;
readln;
end.
This is normal, because we are passing a pointer when dealing with a class -
not passing
the class contents. Which is really what I should have thought about before
asking the
question, because I have discovered you can write to a const class *contents*
before.
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[fpc-pascal] sort procedure of T(FP)List
Hi, i wonder why the declaration of the comparing function of list objects is the way it is: TListSortCompare = function (Item1, Item2: Pointer): Integer; Since I am writing a class that sorts a list it owns depending on another property naming the property of the list items for sorting, I would like to have it made a procedure of object: TListSortCompare = function (Item1, Item2: Pointer): Integer of object; I'm dealing with lists of files and directories that should get sorted by name, date, ... If the comparing function is a plain non object function I have to make some sort of unit global variable or the like for telling it, what property is the sort criteria. I don't like this design, although in this case there is only one soritng process at a time. Is this a concession imposed by Delphi compatibility? (If you can suggest a better strategy for using this stuff, please do.) TIA; Marc ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] eof strangeness
John Coppens wrote:
program testeof;
begin
if eof then
writeln('EOF found')
else
writeln('No EOF found');
end.
This sample program doesn't return till enter is pressed.
That's correct and reasonable. You are terminating your program after an EOL
(ENTER), If
you send it an EOF ^d it also responds reasonably.
$ ./testeof
^d entered at kybd
EOF found
Bob
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[fpc-pascal] string comparison on various platforms
Hi, from digging the sources I know, that on Unix-like Systems the comparison of strings is done according to the current locale (Pascals strcomp is mapped to C-libs strcoll). Can I assume that this is done similar on all other platforms, too? I'm asking myself if I have to consider something special when sorting strings or if a comparison using the RTL function will allways be correct (not talking of special sort orders for rarely occuring cases). TIA, Marc ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] aterm won't run fp
On Tue, 25 Apr 2006 08:52:05 +0200 (CEST) [EMAIL PROTECTED] (Marco van de Voort) wrote: Can anyone tell me what's missing to get aterm to run fp? Implementation of the Xterm terminal standard ? :) Debugging startup (possibly using a simpler example like installer first), is the only real solution I think. Just in case someone bumps into the same problem - Thanks to some suggestions on the IRC channel, I solved the aterm problem with: aterm -tn xterm -e fp Surprisingly 'aterm -tn rxvt -e fp' does not work (but rxvt -e fp does work!) John ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
