[fpc-pascal] with no if assigned() there are bugs

[Mark Morgan Lloyd]

On 21/09/16 06:30, Tomas Hajny wrote:
> On Wed, September 21, 2016 07:29, Lars wrote:
>
>
> Hi,
>
>> Hi all, I am wondering what your thoughts are on this
>> idea: add the ability to do if assigned() on all
>> objects to prevent bugs, maybe as a compiler feature.
>  .
>  .
>
> What would be the supposed "else" clause of your "if" statement? I assume
> that the original action with the given object should not be ignored
> silently, because that would lead to even more difficult debugging of such
> bugs. Run-time error? But that is already happening with access violation
> too. Or...?

Presumably this would be an assertion that something is assigned. A 
related test is that an object is a specific subtype before using it as such

   Assert(PageControl1.ActivePage.Controls[0] is TSynEdit);
   syn := TSynEdit(PageControl1.ActivePage.Controls[0]);

but I'd suggest that this is as much a refactoring problem as one which 
should be tackled by the compiler.

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]