OpenEuphoria

Re: Packages

• Posted by Matt Lewis <matthewwalkerlewis at gm?il.c?m> Aug 09, 2007
• 520 views

Derek Parnell wrote:
> 
> I believe Chris has an exagerated sense of this issue too. It is not a problem
> in the sense that people are tripping up on it all the time and are thus being
> frustrated by the language design. 
> 
> This strikes me as a concept that Chris would like to see implemented because
> its a neat one. And I agree with that. The concept of "packages" for Euphoria
> is a nice one, but the lack of it is not, as we speak, causing any general
> angst.
> 
> I think that if I were to advocate such a concept, I'd do only two things:
> (1) Create a new keyword that defines the scope of an identifier as being
> limited
> to the package. This would work like 'global' but things outside the package
> could not access the identifier.
>   eg.
>  sequence mVersion = "1.0"   -- seen only in containing file
>  package integer vNextID     -- seen only in containing package
>  global constant Foo = "FOO" -- seen only in containing application

This seems sane to me.

> (2) Define the term package as meaning "all the files in the same directory".
> 
> Thus statements in C:\foo\abc.e can access 'package' items in c:\foo\def.e but
> statements in C:\bar\qwerty.e cannot see those 'package' items.

I like this less.  Along with CChris' reservations, I think that this
would complicate the distribution process.  This system reminds me of
java (not the same, obviously, but some real parallels).  Libraries
that used the package functionality would have to be kept in their
directory structure when distributed [as source] with applications.

It's not necessarily a bad thing, but I believe that it's different than
how most people currently use libraries.  Easier might be to use some kind
of a "with package xyz" sort of statement.  Package names would have to
be treated like normal symbol names for resolution purposes, or we end
up in the same mess all over again.

To demonstrate this, suppose that both two math libraries used the same
package:

with package math

Clearly, neither wants to see the other's packaged symbols.  Also, the app
using these libs might want to see the packaged symbols of one, but not
the other:

-- derek_math.e
with package math

-- matt_math.e
with package math

-- my_app.ex
include derek_math.e as dmath
include matt_math.e as mmath
with package dmath:math

The "with package" may not be correct, since it's probably important to 
declare whether you're extending the package or just using it.  Or maybe
not.  

Also, what if you use multiple "with package" statements?  Can
code be part of multiple packages?

What if a symbol is declared as package, but there's no "with package"
directive?

Are only things surrounded by with/without package included in the package?

No doubt there are more questions that need to be answered. 

Matt