strange behaviour with package and namespace

[pd]

I'm trying the diagram implementation listed in [1] which provides an example and a link to a package file.

I've downloaded the package file (diagram.tcl) and copied the example in a tcl file (test_diagram.tcl)

I have a problem using the package diagram. But after loading successfully the package:

% lappend auto_path .
C:/Users/... .
% package require BWidget
1.9.13
% package require diagram
1

but I cannot use it because it doesn't find any command, for example:

% ::diagram::create_diagram
invalid command name "::diagram::create_diagram"

even when the namespace exits:

% namespace exists diagram
1

The namespace defined in package export all symbols (namespace export *) so I've tried to import them all and try to run the procs withou success:

% namespace import diagram::*
% create_diagram
invalid command name "create_diagram"

I was expecting to execute procs in a namespace when you fully qualified it, but it doesn't work in this case.

What is really strange is it seems to be using a different diagram namespace because if I query for its vars and procs I get:

% info vars ::diagram::*
::diagram::Snit_typemethodInfo ::diagram::Snit_info ::diagram::Snit_optionInfo ::diagram::Snit_methodInfo
% info procs ::diagram::*
::diagram::Snit_methodreset ::diagram::Snit_destructor ::diagram::Snit_constructor ::diagram::Snit_typeconstructor ::diagram::Snit_instanceVars

which seems to be related with Snit and not with the package I have loaded (which defines a diagram namespace with vars like data, minimap_ratio or autoscrolling and procs like create_scroll_minimap, find_port_point_circle or create_diagram)

Any idea about what's happening? maybe is a problem with another package loaded? maybe BWidget?

regards

[saitology9]

On 2/6/2024 5:53 PM, pd wrote:
> I'm trying the diagram implementation listed in [1] which provides an example and a link to a package file.
>
> I've downloaded the package file (diagram.tcl) and copied the example in a tcl file (test_diagram.tcl)
>
> I have a problem using the package diagram. But after loading successfully the package:
>
> % lappend auto_path .
> C:/Users/... .
> % package require BWidget
> 1.9.13
> % package require diagram
> 1
>
> but I cannot use it because it doesn't find any command, for example:
>
> % ::diagram::create_diagram
> invalid command name "::diagram::create_diagram"

I am not familiar with this code but you should be able to get this to
run with the following changes:

1) In the file "diagram.tcl", move the statement "package provide ..."
from the top to the bottom of the file.

2) In the "test_diagram.tcl" file, change all instances of
"diagram::xyz" to "::diagram::xyz".

[pd]

El martes, 6 de febrero de 2024 a las 23:53:35 UTC+1, pd escribió:
>
> I have a problem using the package diagram. But after loading successfully the package:
>
> % lappend auto_path .
> C:/Users/... .
> % package require BWidget
> 1.9.13
> % package require diagram
> 1
>
> but I cannot use it because it doesn't find any command, for example:
>
> % ::diagram::create_diagram
> invalid command name "::diagram::create_diagram"
>
> even when the namespace exits:
>
> % namespace exists diagram
> 1
>

> What is really strange is it seems to be using a different diagram namespace because if I query for its vars and procs I get:
>
> % info vars ::diagram::*
> ::diagram::Snit_typemethodInfo ::diagram::Snit_info ::diagram::Snit_optionInfo ::diagram::Snit_methodInfo
> % info procs ::diagram::*
> ::diagram::Snit_methodreset ::diagram::Snit_destructor ::diagram::Snit_constructor ::diagram::Snit_typeconstructor ::diagram::Snit_instanceVars
>

I managed to solve the problem, apparently the package was loaded right but it's an illusion, really the package that was loaded with

% package require diagram

is the tcllib diagram package which happens to be also version 1.0 and also defines a diagram namespace, for this reason all procs and vars in the namespace are so strange, they are from tcllib diagram rather than diagram.tcl

I solved it making the diagram.tcl a module (pm) rather than a package, so I can better control which one is loading.

This issue makes me to realize about the problem of name collision between packages, I think it should be managed but don't know how because there's no proper mechanism , maybe a hierarchy name similar to java packages.

Also I have another problem with tcllib package (I've played with it after this problem) but I'll discuss it in another post.

[pd]

El miércoles, 7 de febrero de 2024 a las 2:10:15 UTC+1, saitology9 escribió:

> I am not familiar with this code but you should be able to get this to
> run with the following changes:
>
> 1) In the file "diagram.tcl", move the statement "package provide ..."
> from the top to the bottom of the file.
>
> 2) In the "test_diagram.tcl" file, change all instances of
> "diagram::xyz" to "::diagram::xyz".

thanks for the ideas, I solved it another way but your reply made me think about...

Is it important where you put the "package provide" in the source file? I supposed it is mainly declarative, independently of where it comes

I also thought ::X::y and X::y to be analogous, like an alias... but maybe X::y is relative to current namespace rather than relative to root namespace and thus ::X::y is not the same of X::y

[Rich]

pd <euke...@gmail.com> wrote:
> I also thought ::X::y and X::y to be analogous, like an alias...

No, those two are not analogous.

> but maybe X::y is relative to current namespace

It is. So X::y will only resolve to ::X::y provided you do not have a
sub X namespace in your current namespace.

> rather than relative to root namespace and thus ::X::y is not the
> same of X::y

No, those two are not identical. X::y just ends up finding ::X::y
because of the namespace name lookup rules, and then only when you
don't have an X namespace below where you are.

If you have this

::X

Then in ::X just Y will look for ::Y as part of the name resolution.

But if you have this:

::X::Y

Then when in ::X, just Y will find ::X::Y and not ::Y (even if you also
have a ::Y).

[Harald Oehlmann]

May I also underline, that the name resolution changed in 9.0.
9.0 does not try any more to resolve in the global namespace without
prefixed "::". So, in 9.0 it will "X::y" will only work from the global
namespace, "::X::y" will work from any namespace.

Harald