[fpc-pascal] Re: How to avoid namespace name clashes after USES ?

[Marcos Douglas]

On Tue, Aug 21, 2012 at 1:43 PM, Timothy Madden <terminatorul at gmail.com> wrote:
> On 08/21/2012 03:10 PM, Jorge Aldo G. de F. Junior wrote:
>> "With no error messages, or even with no changes to the program since 1
>> and a half year in the repository, the scientific calculations are now
>> all blown up, and program outputs only errors at runtime. The maintainer
>> now curses and chases me for having the nerve to leave a program
>> known as working in such a horrible mess in the repository."
>>
>> Never tested, but doesnt the compiler warn of the colision ? if not, it should.
>
> The problem is the language exposes my program to the risk of future
> collisions from the units I use.

Yes.

> A warning is a little beyond the scope of this problem, because my
> program is working perfectly as of now.
>
> But next year, some unit I use will have reached a new version, and if I
> merely recompile my program I have already have a conflict, that was not
> there last year.

Yes.

> And the new version for the unit in question is fully compatible with
> the old one, so you would say my code should still compile.
>
> The question here is if it would be possible for the language to prevent
> this problem, like python (and others) do.

Obligatorily, not.
You can use a pratice to use unit.func always or, as I do, use a
prefix in all identifiers:
unit: foo_unitname
proc/func: fooProc, fooFunc  -- maybe use class procedure/function instead.
classes: TfooClass
global var: DO NOT USE!
global consts: FOO_CONST_NAME -- maybe use class const instead.

> Otherwise, I could never upgrade a library, even if the vendor announces
> full compatibility with the previous version. Because I will still
> expose my old code to the risk of new collisions.
>
> Even worse, as the language currently stands, it is possible to upgrade
> a unit to a compatible version and get a different behaviour from my
> program. Without a single warning from the compiler.

Yes, Yes, even people saying otherwise.

Marcos Douglas