Re: [fpc-pascal] LongBool True = -1

[Sven Barth via fpc-pascal]

Dmitry Boyarintsev  schrieb am So., 20. Mai
2018, 04:38:

> On Thu, May 17, 2018 at 5:26 PM, Anthony Walter  wrote:
>
>> I am working with some a glib library that expects gboolean to be
>> positive 1 for true, yet FPC emits -1 for true.
>>
>
> I'd think that pascal defines true as
>   true = not false;
> In case of unsigned integers "-1" is not an option
>

FPC defines True as 1 for Boolean, Boolean16, Boolean32 and Boolean64 and
as "-1" aka "all bits 1" for Byte Book, WordBool, LongBool and QWordBool.

And for unsigned integers "-1" is converted to "all bits 1" as well though
one needs to use a typecast (see the declaration of INVALID_HANDLE_VALUE
for example).

Regards,
Sven
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Re: [fpc-pascal] LongBool True = -1

[Dmitry Boyarintsev]

On Thu, May 17, 2018 at 5:26 PM, Anthony Walter  wrote:

> I am working with some a glib library that expects gboolean to be positive
> 1 for true, yet FPC emits -1 for true.
>

I'd think that pascal defines true as
  true = not false;
In case of unsigned integers "-1" is not an option

thanks,
Dmitry
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Re: [fpc-pascal] LongBool True = -1

[Sven Barth via fpc-pascal]

Gerhard Scholz  schrieb am Sa., 19. Mai 2018, 19:51:

> Afaik, the bool types (longbool, wordbool, bytebool) come from the C
> language and are mostly used to interface with C libraries (for example:
> windows). The definitions there are: 0 means FALSE, anything else means
> TRUE. Normally C routines return a dword/word/byte filled with ones for
> TRUE
> and expect something not 0 as TRUE. So, the definition comes from C. As
> long
> Pascal programmers want to use libraries written in C, this definition
> should not be changed in the Pascal compiler.
>

For glib that is not true. See my quote from their documentation. Also that
library is the main reason that the Boolean32 type exists (Boolean16 and
Boolean64 were logical extensions then).

Regards,
Sven

>
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Re: [fpc-pascal] LongBool True = -1

[Gerhard Scholz]

Afaik, the bool types (longbool, wordbool, bytebool) come from the C 
language and are mostly used to interface with C libraries (for example: 
windows). The definitions there are: 0 means FALSE, anything else means 
TRUE. Normally C routines return a dword/word/byte filled with ones for TRUE 
and expect something not 0 as TRUE. So, the definition comes from C. As long 
Pascal programmers want to use libraries written in C, this definition 
should not be changed in the Pascal compiler.


Regards
Gerhard

- Original Message - 
From: "Sven Barth via fpc-pascal" <fpc-pascal@lists.freepascal.org>

To: <fpc-pascal@lists.freepascal.org>
Cc: "Sven Barth" <pascaldra...@googlemail.com>
Sent: Friday, May 18, 2018 7:22 AM
Subject: Re: [fpc-pascal] LongBool True = -1



Am 17.05.2018 um 23:26 schrieb Anthony Walter:
I am working with some a glib library that expects gboolean to be 
positive 1 for true, yet FPC emits -1 for true. Is there a compiler flag 
to force boolean types to emit 1 instead of -1? If so, would there 
possibly be any side effects with other pascal code?
Why don't you use the glib2 unit which declares a correct gBoolean type 
(using Boolean32 which had been introduced for that purpose) and 
accordingly defined gTRUE and gFALSE?


Regards,
Sven
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Re: [fpc-pascal] LongBool True = -1

[Sven Barth via fpc-pascal]

Am 17.05.2018 um 23:26 schrieb Anthony Walter:
I am working with some a glib library that expects gboolean to be 
positive 1 for true, yet FPC emits -1 for true. Is there a compiler 
flag to force boolean types to emit 1 instead of -1? If so, would 
there possibly be any side effects with other pascal code?
Why don't you use the glib2 unit which declares a correct gBoolean type 
(using Boolean32 which had been introduced for that purpose) and 
accordingly defined gTRUE and gFALSE?


Regards,
Sven
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[fpc-pascal] LongBool True = -1

[Anthony Walter]

I am working with some a glib library that expects gboolean to be positive
1 for true, yet FPC emits -1 for true. Is there a compiler flag to force
boolean types to emit 1 instead of -1? If so, would there possibly be any
side effects with other pascal code?
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