[fpc-pascal] readonly variables

Mehmet Erol Sanliturk sanliturk at ttmail.com
Sun Nov 29 21:28:49 CET 2009

Jonas Maebe wrote:
> On 29 Nov 2009, at 19:20, Mehmet Erol Sanliturk wrote:
>> My experience with Windows XP Professional is that it is NOT zeroing the memory . 

I know this from actual Delphi ( and also Free Pascal ) compiled program 
executions .

Due to this I am explicitly initializing all of the local simple 
variables ,

elements of records .
> The discussion was about global variables, not about local variables. 

Local variables are indeed not initialised (not in FPC nor in Delphi/TP).
> Jonas

Dear Jonas ,

I am sorry about my misunderstanding .

We may think the global variables are placed in memory which is not 
cleaned by operating system before starting the program . Therefore it 
is necessary to initialize them . In a FreeBSD mailing list thread this 
point is discussed about security vulnerability by complaining about a 
package that it was not cleaning its global/local variables before 
terminating and leaving values of them in memory ( this shows that 
FreeBSD is NOT clearing memory itself running that package ) .

My habit is nearly in all of my programming life ( even in BASIC ) to 
initialize all of the variables by myself . Now , I am removing almost 
ALL of the global variables by making them local to starting procedures 
. If I can not do that , nearly ALL of my global variables are placed 
into RECORD declarations to prevent accidental effects of local variable 
declarations with the same name hiding the global variable ( therefore 
causing nearly impossible to find bugs ) .

This shows reason of my misunderstanding because for me there is no such 
an initialization by compilers concept .

Thank you very much .

Mehmet Erol Sanliturk

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