[fpc-pascal] Thread Safety of String

[Michael Van Canneyt]

On Wed, 4 Jun 2014, johanns at nacs.net wrote:

> On Wed, Jun 04, 2014 at 01:19:33PM -0400, md at rpzdesign.com wrote:
>> On 6/4/2014 1:16 PM, Michael Van Canneyt wrote:
>>> 
>>> 
>>> On Wed, 4 Jun 2014, md at rpzdesign.com wrote:
>>> 
>>>> Hello:
>>>> 
>>>> Is a string[30] declaration under Linux thread safe?
>>> 
>>> No.
>>> 
>>> Michael.
>> 
>> Just as I suspected.
>> 
>> So every time a new value is assigned to a string[30] variable, memory
>> is allocated and changed by the compiler, so the internal string pointer
>> changes as well.
>> 
>> And the only recourse is critical sections for memory access.
>> 
>> Correct?
>> 
>> CHeers,
>> 
>> marco
>
> I still program in Turbo Pascal so I am more of a spectator than a user of 
> Free Pascal.  As I understand it the shortstring type is the same as string 
> type in Turbo Pascal.  This would make index 0 of variable typed as 
> shortstring[SIZE] an internal length byte and index positions 1 through SIZE 
> the data value of the string.  Since, unlike a newer string type, a 
> shortstring is not an object and not a managed string at all, but a simple 
> type like an integer, I would expect shortstring might be thread safe.
>
> Is this the case?

No, exactly the opposite.

Michael.