Re: TINYINT set as signed in formcontrolfactory.cxx

On Sat, Jan 12, 2013 at 08:43:53PM +0100, Alexander Thurgood wrote:

> I came across this in the file formcontrolfactory.cxx, which has
> left me a bit puzzled :

> sal_Int32 nDataType = DataType::OTHER;
>             OSL_VERIFY( _rxDatabaseField->getPropertyValue(
> FM_PROP_FIELDTYPE ) >>= nDataType );
>
>             if  (   xModelPSI->hasPropertyByName( FM_PROP_VALUEMIN )
>                 &&  xModelPSI->hasPropertyByName( FM_PROP_VALUEMAX )
>                 )
>             {
>                 sal_Int32 nMinValue = -1000000000, nMaxValue = 1000000000;
>                 switch ( nDataType )
>                 {
>                     case DataType::TINYINT  : nMinValue = 0; nMaxValue =
> 255; break;
>                     case DataType::SMALLINT : nMinValue = -32768;
> nMaxValue = 32767; break;
>                     case DataType::INTEGER  : nMinValue = 0x80000000;
> nMaxValue = 0x7FFFFFFF; break;
>                         // double and singles are ignored
>                 }

> In particular, the line :

> case DataType::TINYINT  : nMinValue = 0; nMaxValue = 255; break

> sets TINYINT as signed.

It sets it as *un*signed.

This code seems to match the behaviour of Microsoft SQL Server.

It is exactly the opposite of the capabilities of LibreOffice's
internal system with 8-bit integers (most notably the "Any" type; see
http://lists.freedesktop.org/archives/libreoffice/2012-December/043160.html )

In MySQL, any integer type can be signed or unsigned. Most database
engines don't allow that choice (they simply use signed, except
tinyint in Microsoft SQL Server which is always unsigned). See the
first/best answer at
http://stackoverflow.com/questions/2991405/what-is-the-difference-between-tinyint-smallint-mediumint-bigint-and-int-in-s


The central question is: what are the consequences of this code? If it
somewhat restrains user input, we should probably set it to cover
signed and unsigned:

  case DataType::TINYINT  : nMinValue = -127; nMaxValue = 255; break;
  case DataType::SMALLINT : nMinValue = -32768; nMaxValue = 65535; break;
  case DataType::INTEGER  : nMinValue = 0x80000000; nMaxValue = 0x7FFFFFFF; break;

Err... But this will not cover unsigned (32 bit) integer, and neither
will it cover any BIGINT :-(

Pff... This could become a mess to handle.

> Oh, and if anyone happens to know where the Default font for form
> controls is defined, I would be most obliged ;-)

Controls where? In a Form? Isn't it the default font of the underlying
Writer document?

-- 
Lionel