Hi,
Recently I learned that you can have writeable typed constants. That
sounds rather like an oxymoron to my. Writeable constants make no sense,
is that then simply a variable? What is the use of a writeable typed
constant?
Below is two examples of how they can be used, and support for them are
Graeme Geldenhuys schreef:
Hi,
Recently I learned that you can have writeable typed constants. That
sounds rather like an oxymoron to my. Writeable constants make no sense,
is that then simply a variable? What is the use of a writeable typed
constant?
Backwards compatibility with turbo
Vincent Snijders wrote:
Backwards compatibility with turbo pascal, which lacked initialized
variables and writable constants were the alternative.
Thanks Vincent. The Kylix 3 help mentioned early versions of Delphi and
Borland Pascal, which made me think that it must have been some
limitation
On Thursday 18 June 2009 08:51:13 Vincent Snijders wrote:
Graeme Geldenhuys schreef:
Hi,
Recently I learned that you can have writeable typed constants. That
sounds rather like an oxymoron to my. Writeable constants make no sense,
is that then simply a variable? What is the use of a
fpcl...@silvermono.co.za wrote:
Is this likely to be dropped in future versions of FPC?
No idea. But I have noticed that FPC (mode objfpc) defaults to allow
writeable typed constants, whereas Delphi and Kylix doesn't. In the
latter two compilers you have to enable is support with $J+ compiler
I don't know (have not tested) what FPC does with mode delphi though.
OK, just tested FPC modes objfpc and delphi. In both cases writeable
typed constants are allow by default. This is not compatible with
current Delphi compilers.
I still think this should be disable by default in both
On Thursday 18 June 2009 10:48:57 Graeme Geldenhuys wrote:
I don't know (have not tested) what FPC does with mode delphi though.
But seeing that this feature is just for backward compatibility, maybe
it should be disallowed by default in mode objfpc as well?
It also works in Delphi mode.
Graeme Geldenhuys schreef:
I don't know (have not tested) what FPC does with mode delphi though.
OK, just tested FPC modes objfpc and delphi. In both cases writeable
typed constants are allow by default. This is not compatible with
current Delphi compilers.
I still think this should be
Vincent Snijders wrote:
I disagree. It would be backwards incompatible with existing objfpc
programs. That decision should have been made 10 (?) years ago, when
mode objfpc was introduced.
Not everything was done correctly 10 years ago (or first time round).
There are many bug reports still
Graeme Geldenhuys schrieb:
Vincent Snijders wrote:
I disagree. It would be backwards incompatible with existing objfpc
programs. That decision should have been made 10 (?) years ago, when
mode objfpc was introduced.
Not everything was done correctly 10 years ago (or first time round).
It's intersting to note that as far back as Delphi 5,(oldest I have on my
system), attempting to write to a typed constant causes a left side cannot
be assigned to compiler error.
I guess as long as FPC compiler offers TP7 compatibility, this feature must be
retained. Also, bear in mind that
In our previous episode, Florian Klaempfl said:
Not everything was done correctly 10 years ago (or first time round).
Nevertheless, writable typed constants are simply an important part of
Borland style Object Pascal.
Is it, since D4 also supports var? I agree it is a sterile difference,
Florian Klaempfl wrote:
Nevertheless, writable typed constants are simply an important part of
Borland style Object Pascal.
I'm not arguing that. Then maybe writeable typed constants should be
disabled for compiler mode delphi at least. It's a Delphi compatibility
issue after all.
Just this
Graeme Geldenhuys wrote:
FPC often implements something that breaks existing code.
Examples :)?
Please note that I am not saying I disagree with the changes. I know
they were introduced for the better. What I am saying, is that changes
do get introduced into FPC (for whatever
Martin Friebe wrote:
Afaik 1 3 are the same?
True.
And if I understand the changes where mad, because this feature was
broken before:
To quote myself, even though I know one shouldn't. ;-)
I know they were introduced for the better.
I was not arguing the point that those changes
Martin wrote:
Just got a question, to ensure I understand thinks correctly.
Let's start with stuff I definitely know (or think so).
Destructors are virtual/overriden, because they are called on the
instance, and the instance may be assigned to a variable foo: Tobject,
which would call
2009/6/18 Graeme Geldenhuys grae...@opensoft.homeip.net
Vincent Snijders wrote:
Backwards compatibility with turbo pascal, which lacked initialized
variables and writable constants were the alternative.
Thanks Vincent. The Kylix 3 help mentioned early versions of Delphi and
Borland
Paul Nicholls schrieb:
I also find writable constants hand for things like this where I can
define the 'variable' + values too so I don't have to set the values at
run time:
But can't you do the same with a variable declaration? If you want to
change the value at runtime it's definitely
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