Re: [fpc-devel] RFC: changing conditional compilation
Hi Jonas,
As you can imagine I'd prefer to solve the $ifdef problem ;-)
To be honest: no, I can't imagine why you would prefer that. The entire
difference between $ifdef and $if is that $if checks the value of something
(and hence will give an error if the symbol is undefined) and $ifdef checks
whether it is defined or not. As far as I can tell, you would simply like to
be able to use boolean constants in $if expressions.
Hope you rethink your opinion the next time you forget to add an {$I}
or mess up a define name ;-)
Best regards,
Flávio
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Re: [fpc-devel] RFC: changing conditional compilation
On 09 Feb 2010, at 01:24, Flávio Etrusco wrote:
As far as I know, that's how macros behave.
E.g.:
{$macro on}
{$define xxx:=1}
{$if xxx}
begin
end.
{$endif}
If you undefine xxx, you'll get a compile time error.
Downside: they don't work with booleans for some reason, only with
integers...
Hi Jonas,
As you can imagine I'd prefer to solve the $ifdef problem ;-)
To be honest: no, I can't imagine why you would prefer that. The
entire difference between $ifdef and $if is that $if checks the value
of something (and hence will give an error if the symbol is undefined)
and $ifdef checks whether it is defined or not. As far as I can tell,
you would simply like to be able to use boolean constants in $if
expressions.
Yes, I noticed the problem with bools - and that it would fail with
string found but boolean expected if the name was undefined -,
The latter is the behaviour you want, no?
Jonas
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Re: [fpc-devel] RFC: changing conditional compilation
2010/2/9 Jonas Maebe jonas.ma...@elis.ugent.be:
On 09 Feb 2010, at 01:24, Flávio Etrusco wrote:
As far as I know, that's how macros behave.
E.g.:
{$macro on}
{$define xxx:=1}
{$if xxx}
begin
end.
{$endif}
If you undefine xxx, you'll get a compile time error.
Downside: they don't work with booleans for some reason, only with
integers...
Hi Jonas,
As you can imagine I'd prefer to solve the $ifdef problem ;-)
To be honest: no, I can't imagine why you would prefer that.
Because everybody automatically uses $ifdef and most of the code would
work with minor intervention. E.g. we usually use something like
{.$define EnableDocking} to undefine the symbol. You'd just have to
force it explicitly $undef or some kind of {$define EnableDocking
disable} or 'false', or something.
The entire
difference between $ifdef and $if is that $if checks the value of something
(and hence will give an error if the symbol is undefined) and $ifdef checks
whether it is defined or not. As far as I can tell, you would simply like to
be able to use boolean constants in $if expressions.
This would solve the problem for my code, not conditionals I'm trying
to use on 3rd party code...
Yes, I noticed the problem with bools - and that it would fail with
string found but boolean expected if the name was undefined -,
The latter is the behaviour you want, no?
Yes - apart from puzzling error message to the casual users - but it'd
require to set a convention on the Macro value for on/off and back to
possibly causing errors due to typos.
Jonas
PS: please reply to the list___
Sorry, I just skip the list sometimes when I think the post will be
just noise to other people. I'd certainly get back to it when I have
something relevant to say ;-)
Best regards,
Flávio
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Re: [fpc-devel] RFC: changing conditional compilation
On 09 Feb 2010, at 00:01, Flávio Etrusco wrote:
Now there's Macros, but they
wouldn't solve the problem either, unless you'd use some crazy scheme
with $if declared or something AFAICS.
What I wished is to change (or add a directive to change) the way
$ifdef/ifndef work, enforcing that symbols are always declared, like
it was a boolean. So one would have to use e.g. {$define EnableFeature
false} to undefine it, otherwise conditionals would fail.
As far as I know, that's how macros behave.
E.g.:
{$macro on}
{$define xxx:=1}
{$if xxx}
begin
end.
{$endif}
If you undefine xxx, you'll get a compile time error.
Downside: they don't work with booleans for some reason, only with integers...
Jonas___
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