[fpc-pascal] Can variables be declared within a block?

[Florian Klaempfl]

Am 18.10.2010 14:58, schrieb Frank Church:
> 
> 
> On 18 October 2010 07:49, Florian Klaempfl <florian at freepascal.org
> <mailto:florian at freepascal.org>> wrote:
> 
>     Am 18.10.2010 08:17, schrieb Zaher Dirkey:
>     >
>     >
>     > On Thu, Oct 14, 2010 at 11:21 AM, Michael Van Canneyt
>     > <michael at freepascal.org <mailto:michael at freepascal.org>
>     <mailto:michael at freepascal.org <mailto:michael at freepascal.org>>> wrote:
>     >
>     >
>     >
>     >     On Thu, 14 Oct 2010, Frank Church wrote:
>     >
>     >         Can variables be declared within a begin end block?
>     >
>     >
>     >     No.
>     >
> 
> 
> That is a rather emphatic no :).
>  Is there some performance or other related reason why it is a bad idea?

It's just a matter of readability, e.g. having a variable declared in
two blocks with the same name can cause you a lot of headache:

procedure p;

begin
  ...
  begin
    var i : integer;
    ...
    ...
    ...
    i:=12341234;
    ...
    ...
    ...
    ...
  end;
  ...
  ...
  ...
  begin
    var i : integer;
    ...
    writeln(i); <--- this i is not the same as above so i does not
contain 12341234 but it contains probably some garbage.
  end;