[Dcmlib] Never trust the programer :)

[Mathieu Malaterre]

Benoit,

	I just added an assert for kick and it is seg faulting. For instance:

   DataEntry *entry = GetDataEntry(0x0020,0x0032);
    if( !entry )
    {
       gdcmWarningMacro( "Unfound Image Position Patient (0020,0032)");
       entry = GetDataEntry(0x0020,0x0030);
       if( !entry )
       {
          gdcmWarningMacro( "Unfound Image Position (RET) (0020,0030)");
          return 0.0f;
       }
    }

    if( entry->GetValueCount() == 3 )
    {
       gdcmAssertMacro( entry->IsValueCountValid() );
       return (float)entry->GetValue(0);
    }
    return 0.0f;

so if 0x0020,0x0032 is not found, you check 0x0020,0x0030, which is then 
found. But if it is found THEN you compare entry->GetValueCount() 
against 3, but how do you know that VM is the same for 0020,0032 and 
0020,0030 ?

Anyway this could have been safe, unfortunately 0020,0030 was entered as 
VM=1 in the dict.

Question: Is this safe to let the programmer use GetValueCount ? Or 
should we enforce IsValueCountValid ? Maybe an alternative would be to 
run IsValueCountValid on the whole gdcmData just to see how respectful 
the DICOM data are to 'our' dict...

Mathieu