[fpc-pascal] Re: Library for network calculation

[Sven Barth]

On 27.07.2011 12:22, Dimitri Smits wrote:
> don't have a Delphi in reach for the moment to verify, but you could do that to a const (if you enable the assignable constants setting)
>
> procedure SomeProc;
> const
>    someconst: Integer = 22;
> begin
>    //blabla
>    someconst := 42;
>    //yadda yadda
> end;
>

In this case "someconst" will keep the assigned value during different 
functions calls.

For example:

=== source begin ===

procedure SomeProc;
const
   someconst: Integer = 21;
begin
   if someconst = 42 then
     Writeln('The answer')
   else begin
     Writeln('Not the answer');
     someconst := 42;
   end;
end;

begin
   SomeProc;
   SomeProc;
end;

=== source end ===

will print:

=== output begin ===

Not the answer
The answer

=== output end ===

This was considered as the equivalent of a local static variable.

In case of "var" the definitions are normal variables and semantically 
equivalent to an initialization of the variable at the beginning of the 
function.

Regards,
Sven

>
> ----- "Sven Barth"<pascaldragon at googlemail.com>  schreef:
>
>> Well... seems like you didn't notice this feature yet :D
>>
>> I'm talking about this:
>>
>> === source begin ===
>>
>> procedure SomeProc;
>> var
>>     somevar: Integer = 42;
>> begin
>>
>> end;
>>
>> === source end ===
>>
>> This works in FPC, but doesn't in Delphi ;)
>>
>> Regards
>> Sven
>>
>> Am 26.07.2011 21:27, schrieb Jorge Aldo G. de F. Junior:
>>> I dont like to take local variable initialization for granted.
>>>
>>> Even if the manual says that its guaranteed that a local variable
>> will
>>> start with 0,
>>> i prefer to initialize everything to a known value myself.
>>>
>>> An aditional
>>>
>>> Move $varaddress, 00
>>>
>>> at startup wont slow things down noticeably when your pc is running
>> at 2ghz...
>>>
>>> This unit needs to take care of big endian vs. low endian (maybe a
>> $define ?)
>>>
>>> When i wrote that code i did not pay attention to this...
>>>
>>> Anything more complex (like interacting with DHCP server) would be
>> too
>>> complex and probably dependent on external units (like synapse x
>> lnet
>>> etc). Some people might prefer to use other library instead of the
>>> default choosen one, etc...
>>>
>>> 2011/7/26 Sven Barth<pascaldragon at googlemail.com>:
>>>> On 26.07.2011 01:23, Paul Nicholls wrote:
>>>>>
>>>>> "Jorge Aldo G. de F. Junior"
>>>>> <jagfj80 at gmail.com>     wrote in message
>>>>>
>> news:CAAHHabS9aUe9gwyNjkve-XVXsRyf2UPsArh6=fSDPGoKugjfsA at mail.gmail.com...
>>>>>>
>>>>>> Some time ago someone asked for a library able to do network
>>>>>> calculations.
>>>>>>
>>>>>> Here is something that might evolve into such library :
>>>>>>
>>>>> <SNIP>
>>>>>>
>>>>>> Function NetMaskToHostMask(NetMask : TNetworkIP): TNetworkIP;
>>>>>> Begin
>>>>>> Result.Mode := False;
>>>>>> NetMask.Mode := False;
>>>>>> Result.IP := NetMask.IP Xor %11111111111111111111111111111111;
>>>>>> End;
>>>>>>
>>>>> <SNIP>
>>>>>
>>>>> I didn't know that freepascal handled binary formatted numbers?!?
>>>>>
>>>>> %11111111111111111111111111111111
>>>>
>>>> There are often new things one can learn about what FPC supports ;)
>> (though
>>>> binary numbers are already old for me ^^)
>>>>
>>>> The most recent finding (at least for me) was the abbility to
>> initialize
>>>> local variables.
>>>>
>>>> Regards,
>>>> Sven
>>>>
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