From Newsgroup: comp.lang.tcl

I'm trying to make a package that is meant to be used as a widget.
This prototype is called testpkg. Here are the files:

-- pkgIndex.tcl

package ifneeded testpkg 1.0 [list source [file join [list $dir] testpkg.tcl]] ----------------

-- testpkg.tcl

package provide testpkg 1.0

namespace eval testpkg {}
proc testpkg {args} {
package require Tk
package require tile

set ::testpkg::args $args
namespace eval ::testpkg {
namespace export testpkg

set ::testpkg::version 1.0

# ----------------
# Processing arguments
set wpath [lindex $args 0]
set wparentsplit [split $wpath "."]
set wparentsplit [lrange $wparentsplit 0 [expr {[llength $wparentsplit] - 2}]]
set wparent [join $wparentsplit "."]
if {[winfo parent $wparent] == 0} {error "Invalid parent path $wpath"}

# ----------------
# Here be widgets
set of $wpath
frame $of -height 100 -width 20
pack $of -fill both -expand 1
set fb $wpath.filelistbox
text $fb
$fb configure -font {Freesans 14} -height 2 -width 20
pack $fb -fill both -expand 1
$fb insert end "This is a test.\nLine 2."
}
}
----------------


If I 'set wpath .top' and run 'testpkg' at this point, the text widget
looks good.

However, I had to test it in a real example:

-- test.tcl

package require Tk
package require tile
package require testpkg

wm withdraw .
set ::w [toplevel .test -background #c0c0c0]
wm title $::w "test"
tk appname "test"

bind $::w <Escape> {exit 0}
wm protocol $::w WM_DELETE_WINDOW {exit 0}

set of $::w.outerframe
frame $of -height 100
pack $of -fill both -expand 1

set fb $of.testpkg
puts "fb $fb"
testpkg $fb
pack $fb -fill both -expand 1
----------------

And it works. Yes, no problem.

So my question is, am I really doing this correctly? Is this really
how it's supposed to be done? Will it work as expected from a widget?
Am I handling the widget path correctly? Is it going to play ball
nicely when inserted into someone else's Tk application?
--
Luc

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

Luc <luc@sep.invalid> wrote:

I'm trying to make a package that is meant to be used as a widget.
This prototype is called testpkg. Here are the files:

-- pkgIndex.tcl

package ifneeded testpkg 1.0 [list source [file join [list $dir] testpkg.tcl]]

Looks typical. If created by "pkg_mkIndex" then it is almost always
correct.

----------------

-- testpkg.tcl

package provide testpkg 1.0

namespace eval testpkg {}

Empty testpkg namespace, created not in the root/global namespace but
in whatever namespace the "package require" is run within. If this is
what you want, it is fine. If you meant for this to always be a
namespace anchored at the root (global) then you'll want ::testpkg to
force it to be anchored there.

proc testpkg {args} {

A proc, created at the global level, outside of any namespace, which,
oddly, then goes on to create a namespace in the root (which may
produce two "testpkg" namespaces if the "package require" for this is
run within a namespace other than the root.

package require Tk
package require tile

set ::testpkg::args $args
namespace eval ::testpkg {
namespace export testpkg

set ::testpkg::version 1.0

# ----------------
# Processing arguments
set wpath [lindex $args 0]

set wparentsplit [split $wpath "."]
set wparentsplit [lrange $wparentsplit 0 [expr {[llength $wparentsplit] - 2}]]
set wparent [join $wparentsplit "."]

Why three lines of ugly split and lrange code to get the parent window
name, when [winfo parent] already gives the parent window name.

if {[winfo parent $wparent] == 0} {error "Invalid parent path $wpath"}

winfo parent returns a window path, or empty string, so it will never
equal zero here, and this will never trigger. Perhaps you meant
'== ""' here?

And, why four lines of "parent" games, and wparent is never again used?
The error call implies you were checking for something, but it is not
clear what you were trying to check for.

# ----------------
# Here be widgets
set of $wpath
frame $of -height 100 -width 20
pack $of -fill both -expand 1
set fb $wpath.filelistbox
text $fb
$fb configure -font {Freesans 14} -height 2 -width 20
pack $fb -fill both -expand 1
$fb insert end "This is a test.\nLine 2."
}
}
----------------

If I 'set wpath .top' and run 'testpkg' at this point, the text widget
looks good.

So my question is, am I really doing this correctly?

That depends upon one's definition of "correctly". You have a package
that per your message, works. So it is "correct" given a definition of
"does not error out with a syntax or logic error".

But you also have some oddness, that could be deemed "incorrect".

I.e., the global "testpkg" proc, defined outside of the namespace,
which then defines some things inside the namespace, is not quite right
for at least the reason that it is polluting the global namespace with
extra procs that don't belong there.

As well, your way of "passing arguments" in, while "it works" is not at
all the normal way of doing so. So that /could/ also be considered "incorrect" in some definitions.

Is this really how it's supposed to be done?

Well, no, not really. Your package should only produce one globally
visible item, the namespace name that the rest of your code is inside.
So the global proc is pollution that is exactly what namespaces were
created to avoid.

As well, you should be passing arguments into procs to build widgets,
not calling a proc that plays games with namespace name paths of define variables and pass in arguments in a roundabout way.

Also, every time you call your global proc, you are redefining the
namespace all over again, which while it isn't harmful in this simple
example will likely eventually create you great grief when you begin to
want to store some long term state in the namespace to support the
widget, but you destroy that state with each new widget you create.

Here's a much simplified version that (to the extent I can tell)
produces the identical results, and avoids the unusual usages above:

namespace eval testpkg {

# make sure our required dependencies are available
package require Tk
package require tile

variable version 1.0

proc make-widget {wpath} {
frame $wpath -height 100 -width 20
pack $wpath -fill both -expand 1
set fb $wpath.filelistbox
text $fb
$fb configure -font {Freesans 14} -height 2 -width 20
pack $fb -fill both -expand 1
$fb insert end "This is a test.\nLine 2."
}

package provide testpkg 1.0
}

And to "create" a "testpkg" widget, you call it somewhere else as:

testpkg::make-widget .abc

Will it work as expected from a widget?

You've not told us what you expect, so we can't really say.

Am I handling the widget path correctly?

You appear to be passing in the path where you want the widget created,
so that's correct (the aspect of "supply the path" to the creation
system, not the way you are passing that path in). As to what you
intended by all the 'wparent' stuff, I honestly don't know what you
were trying to do there.

Is it going to play ball nicely when inserted into someone else's Tk application?

Most likely, but only because someone else's Tk application is not
likely to have a "testpkg" proc at the global level. But, if someone
else does have a 'testpkg' proc at the global level, then it will not
play nicely (as you'll be overwriting someone else's proc with yours
from this package).
--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

On Sun, 31 Mar 2024 15:55:46 -0000 (UTC), Rich wrote:

Empty testpkg namespace, created not in the root/global namespace but
in whatever namespace the "package require" is run within. If this is
what you want, it is fine. If you meant for this to always be a
namespace anchored at the root (global) then you'll want ::testpkg to
force it to be anchored there.

1. That namespace declaration is empty just so the namespace exists
so I can smuggle the $args into it later.

2. Do I want it to be independent of root/global namespace? I honestly
don't know. I really don't suspect what the consequences will be in
either case. Do you recommend something?

proc testpkg {args} {

A proc, created at the global level, outside of any namespace, which,
oddly, then goes on to create a namespace in the root (which may
produce two "testpkg" namespaces if the "package require" for this is
run within a namespace other than the root.

That is a very good point.

The reason I did that is that I don't want the command to be accessible
as ::testpkg::testpkg. I've seen that approach in other packages and
I don't like it. I want it to operate in the global scope like all the
first class built-in widgets. I do have some hope that it will be accepted
as an "official" Tk widget/command in the future. Yes, it creates a testpkg proc, so what? If you run 'package require testpkg' in your code, you
should know what you're doing. You should be aware of the consequences.
This is not ordinary user input. It's something a developer is going to do.

Why three lines of ugly split and lrange code to get the parent window
name, when [winfo parent] already gives the parent window name.

I tried [winfo parent $widget] but that didn't work for me. Tk throws
an error complaining that $widget doesn't exist. It doesn't. It is going
to be created on the next line, but it doesn't exist yet. I am not
checking $widget, I am checking its parent, but [winfo parent] is not
having it. So I had to isolate the parent so I could check it.

And, why four lines of "parent" games, and wparent is never again used?
The error call implies you were checking for something, but it is not
clear what you were trying to check for.

I am checking if the parent exists. I can't append my widget to a path
that isn't valid.

As well, your way of "passing arguments" in, while "it works" is not at
all the normal way of doing so. So that /could/ also be considered >"incorrect" in some definitions.

What would the correct way of passing arguments be?

Also, every time you call your global proc, you are redefining the
namespace all over again, which while it isn't harmful in this simple >example will likely eventually create you great grief when you begin to
want to store some long term state in the namespace to support the
widget, but you destroy that state with each new widget you create.

That sounds concerning, but I don't see how or why the widget/proc
would be called more than once in any code. You run it, interact with
it for as long as needed for it to do its job then it's destroyed.


Thank you for your remarks.
--
Luc

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

Luc <luc@sep.invalid> wrote:

On Sun, 31 Mar 2024 15:55:46 -0000 (UTC), Rich wrote:

Empty testpkg namespace, created not in the root/global namespace but
in whatever namespace the "package require" is run within. If this is >>what you want, it is fine. If you meant for this to always be a
namespace anchored at the root (global) then you'll want ::testpkg to >>force it to be anchored there.

1. That namespace declaration is empty just so the namespace exists
so I can smuggle the $args into it later.

Ok, a bit of experimenting has led me to this sentence in the 'package' manpage:

"If so, the script for the highest acceptable version number is
evaluated in the global namespace;"

So your "namespace eval testpkg {}" is converted to effectively be
"namespace eval ::testpkg {}" by the operation of package require.

Also, why try to 'smuggle' when you can simply pass them to a proc that
lives in the namespace and then the args get there via the method most programmers would expect. Your 'smuggling' will leave folks scratching
their head wondering *why* did you do that because it is a very
unusual way to pass parameters to a proc.

2. Do I want it to be independent of root/global namespace? I honestly
don't know. I really don't suspect what the consequences will be in
either case. Do you recommend something?

From my experimentation it seems it does not matter, 'package require' ultimately drops you into :: before your package code runs anyway.

proc testpkg {args} {

A proc, created at the global level, outside of any namespace, which, >>oddly, then goes on to create a namespace in the root (which may
produce two "testpkg" namespaces if the "package require" for this is
run within a namespace other than the root.

That is a very good point.

Given the docs, you don't accidentally produce two testpkg namespaces,
but you do still pollute the global with your extra proc that
ultimately creates the namespace anyway.

The reason I did that is that I don't want the command to be
accessible as ::testpkg::testpkg. I've seen that approach in other
packages and I don't like it.

Ok, so you have two possible alternatives that are standard fare:

1) mark the inner testpkg proc as exportable, and let the package user
decide which they want to do:

::testpkg::testpkg ...

or

namespace import ::testpkg::*
testpkg ...

And, for your own uses, just import it where you want it and then you
don't have to type out "testpkg::testpkg ..." everywhere.

2) setup the namespace to be an ensemble, with reasonable naming of the ensenble procs, and then you can do:

package require testpkg

testpkg create-widget ...

I want it to operate in the global scope like all the first class
built-in widgets.

Making the procs exportable and then importing them into the global
scope after loading the package accomplishes that goal, with only one
extra command (the namespace import).

I do have some hope that it will be accepted as an "official" Tk widget/command in the future.

Yes, it creates a testpkg proc, so what? If you run 'package require testpkg' in your code, you should know what you're doing.

Yes, but at the same time the user of the package has a reasonable
expectation that the package will create its "stuff" within its
boundaries, rather than outside those boundaries. One of the reasons
for the addition of namespaces to Tcl was to prevent name conflicts
within plural packages that each wanted to use the same name for part
of their operation.

You should be aware of the consequences. This is not ordinary user
input. It's something a developer is going to do.

Yes, and at the same time that developer expects your package to abide
by the "rules" (convention) of packages placing their "stuff" inside
their own "boundaries" instead of filling up the global namespace.

Why three lines of ugly split and lrange code to get the parent
window name, when [winfo parent] already gives the parent window
name.

I tried [winfo parent $widget] but that didn't work for me. Tk
throws an error complaining that $widget doesn't exist. It doesn't.
It is going to be created on the next line, but it doesn't exist yet.
I am not checking $widget, I am checking its parent, but [winfo
parent] is not having it. So I had to isolate the parent so I could
check it.

But why are you checking its parent? If you just care to emit an error message when the path your code has been asked to use is not proper,
then catching errors on creating your 'subframe' works just fine:

try {
frame $wpath.testpkg-frame
} on error {msg opts} {
error "testpkg: Provided widget path: $wpath is invalid.\n$msg"
}

Or, you just go an create the 'frame' and let any errors propagate back normally.

And, why four lines of "parent" games, and wparent is never again
used? The error call implies you were checking for something, but it
is not clear what you were trying to check for.

I am checking if the parent exists. I can't append my widget to a
path that isn't valid.

So wrap it in a try/catch (see above) if you want to customize the
message, or just go and do the frame create. If it errors out and you
have not caught it then the error will propagate back out to the other
user's code to do with as they see fit.

As well, your way of "passing arguments" in, while "it works" is not
at all the normal way of doing so. So that /could/ also be
considered "incorrect" in some definitions.

What would the correct way of passing arguments be?

See my "revised" example of your test package that I included in my
prior reply. Just use the standard proc parameters.

Also, every time you call your global proc, you are redefining the >>namespace all over again, which while it isn't harmful in this simple >>example will likely eventually create you great grief when you begin to >>want to store some long term state in the namespace to support the
widget, but you destroy that state with each new widget you create.

That sounds concerning, but I don't see how or why the widget/proc
would be called more than once in any code. You run it, interact with
it for as long as needed for it to do its job then it's destroyed.

Do you not, often, create more than one "frame" or "button" or even
more than one single "text" widget? If you are thinking of this as
possibly becoming an official 'widget' one day, then you have consider
a broader usage than what you believe your own usage might be. Someone
else very well may want sixteen of these widgets across eight different toplevel windows all at the same time.

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

On Sun, 31 Mar 2024 20:18:02 -0000 (UTC), Rich wrote:

Also, why try to 'smuggle' when you can simply pass them to a proc that >lives in the namespace

Because I don't want ::testpkg::proc. I want proc. In the global scope.

I don't want to "protect" the command. I want the command to be global.
I want the variables to be protected. OK, so maybe I don't need the
namespace, the proc should suffice? I will think about that.

Your 'smuggling' will leave folks scratching
their head wondering *why* did you do that because it is a very
unusual way to pass parameters to a proc.

I am not passing parameters to a proc. I am passing parameters to
a namespace. And that is the only way.

Given the docs, you don't accidentally produce two testpkg namespaces,
but you do still pollute the global with your extra proc that
ultimately creates the namespace anyway.

Does 'text' pollute the global scope?
Does 'scrollbar' pollute the global scope?
Does 'label' pollute the global scope?
It's supposed to be about the same thing.

Ok, so you have two possible alternatives that are standard fare:
1) mark the inner testpkg proc as exportable, and let the package user >decide which they want to do:
::testpkg::testpkg ...
or
namespace import ::testpkg::*
testpkg ...

That sounds like a lot of unnecessary extra work. It is meant to be a
first class command. Sure, only after it is package-required, but still
a first class command. If you want to use it and you already have a
proc with the same name, you are just going to have to rename your
proc. I mean, the odds are really slim.

2) setup the namespace to be an ensemble, with reasonable naming of the >ensenble procs, and then you can do:
package require testpkg
testpkg create-widget ...

That makes the command global like I intend to, but requires that the user/developer call two commands instead of one which doesn't make
sense because the package only has one command. It has -parameters
or -options, but only one command. Just like all the Tk widgets we
are all used to.

Hmm, actually, it is supposed to accept other commands, but I designed
a different interface for them, a trace on the ::testpkg::command var.
And I believe that is the only possible approach because the widget
has to be able to receive the commands after it has been packed/gridded
and is already/still doing its job. These commands cannot be passed at
the time the widget is run/created. That is a pretty good reason to
keep the namespace. I can't put that traced var in the global scope.

Yes, but at the same time the user of the package has a reasonable >expectation that the package will create its "stuff" within its
boundaries, rather than outside those boundaries.

The command will be global. The only remaining "boundaries" is for
variables, and namespaces is the way to do that, right? And there are
no other procs, 'testpkg' is the only proc.

But why are you checking its parent? If you just care to emit an error >message when the path your code has been asked to use is not proper,
then catching errors on creating your 'subframe' works just fine:

try {
frame $wpath.testpkg-frame
} on error {msg opts} {
error "testpkg: Provided widget path: $wpath is invalid.\n$msg"
}

Or, you just go an create the 'frame' and let any errors propagate back >normally.

I guess that would work, but sounds like trading six for half a dozen
to me. My way also works. Or is there something really wrong with it?

One of the reasons
for the addition of namespaces to Tcl was to prevent name conflicts
within plural packages that each wanted to use the same name for part
of their operation.

Do you not, often, create more than one "frame" or "button" or even
more than one single "text" widget? If you are thinking of this as
possibly becoming an official 'widget' one day, then you have consider
a broader usage than what you believe your own usage might be. Someone
else very well may want sixteen of these widgets across eight different >toplevel windows all at the same time.

OK, maybe that is a risk. So instead of creating a 'testpkg' namespace,
I guess I will create a "testpkg_[clock milliseconds]" namespace. Do we
have a deal? :-)
--
Luc

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

Luc <luc@sep.invalid> wrote:

On Sun, 31 Mar 2024 20:18:02 -0000 (UTC), Rich wrote:

Also, why try to 'smuggle' when you can simply pass them to a proc that >>lives in the namespace

Because I don't want ::testpkg::proc. I want proc. In the global scope.

Which you get if you:

1) in the package, 'namespace export' the proc
2) after "package requiring" the package, "namespace import" the
exported procs

Then the rest of your code can use the proc as a global proc (and so
can anyone else who wants to). And those who don't want to can call it
as "testpkg::testpkg".

I don't want to "protect" the command. I want the command to be global.
I want the variables to be protected. OK, so maybe I don't need the namespace, the proc should suffice? I will think about that.

It sounds like you want the namespace to be specific for that one
widget. In which case, use an object. You get an isolated namespace
for the object's variables automatically from the system without you
having to do anything (other than learn a bit of how to use tcloo).

Your 'smuggling' will leave folks scratching their head wondering
*why* did you do that because it is a very unusual way to pass
parameters to a proc.

I am not passing parameters to a proc. I am passing parameters to
a namespace. And that is the only way.

Sigh.... Again... A namespace is not a thing you can call or "pass parameters" to (passing parameters refers to calling things).

Namespaces are simply containers (like a jar or box). They are not
active in and of themselves, and you can't "pass things" to them
because you don't "call them".

Given the docs, you don't accidentally produce two testpkg
namespaces, but you do still pollute the global with your extra proc
that ultimately creates the namespace anyway.

Does 'text' pollute the global scope?
Does 'scrollbar' pollute the global scope?
Does 'label' pollute the global scope?

Those are not considered "pollution" because they existed globally
before Tcl had namespaces, so they remained globals afterwards for
backwards compatibility.

It's supposed to be about the same thing.

And, if you have wishes about this becoming an "official widget" then
you'll eventually have to follow some of the conventions. I.e., for
'tcllib' one of those conventions is your module/package resides
totally within its own namespace:

https://wiki.tcl-lang.org/page/Tcllib+Contribution+%26+Feedback?R=0

* The module must use a namespace for its commands and variables

Ok, so you have two possible alternatives that are standard fare:
1) mark the inner testpkg proc as exportable, and let the package user >>decide which they want to do:
::testpkg::testpkg ...
or
namespace import ::testpkg::*
testpkg ...

That sounds like a lot of unnecessary extra work.

It is one extra line of code for you to write, once.

It is meant to be a first class command. Sure, only after it is package-required, but still a first class command. If you want to
use it and you already have a proc with the same name, you are just
going to have to rename your proc. I mean, the odds are really slim.

Really slim odds happen remarkably often when large numbers are
concerned. By this I mean if it were to gain signifant use (large
numbers of users) those slim odds will tend towards 100% chance of
conflict.

2) setup the namespace to be an ensemble, with reasonable naming of the >>ensenble procs, and then you can do:
package require testpkg
testpkg create-widget ...

That makes the command global like I intend to, but requires that the user/developer call two commands instead of one which doesn't make
sense because the package only has one command. It has -parameters
or -options, but only one command. Just like all the Tk widgets we
are all used to.

It's not two commands, it is command and subcommand (and, yes, a bit
much for a single command package). But it is another alternative.

Hmm, actually, it is supposed to accept other commands, but I designed
a different interface for them, a trace on the ::testpkg::command var.
And I believe that is the only possible approach because the widget
has to be able to receive the commands after it has been packed/gridded
and is already/still doing its job. These commands cannot be passed at
the time the widget is run/created. That is a pretty good reason to
keep the namespace. I can't put that traced var in the global scope.

That's one way, but that's also significantly harder than the
conventional way, which is you set your widget up to work like the rest
of the tk widgets, where creating it (your widget) creates a proc that
can then be called to configure/update/etc. the widget.

I.e., like how 'text' creates a command named after the window path,
and then you call that command to "do things" to the text widget:

i.e.:
text .txtwidget

.txtwidget insert end "Hello World"

And, note that the ".txtwidget" command invocation looks remarkably
similar to how procs in a namespace ensemble are called. That should
give you a hint as to what 'namespace ensemble' is useful for.

Yes, but at the same time the user of the package has a reasonable >>expectation that the package will create its "stuff" within its >>boundaries, rather than outside those boundaries.

The command will be global. The only remaining "boundaries" is for
variables, and namespaces is the way to do that, right? And there are
no other procs, 'testpkg' is the only proc.

Unless the variables are only needed when creating the widget, then
they can just be proc locals. But if the variables have to live on and
hold data for the widget while it is doing its thing, then namespaces
are one way to do that. Objects are another way to also do that.

But why are you checking its parent? If you just care to emit an
error message when the path your code has been asked to use is not
proper, then catching errors on creating your 'subframe' works just
fine:

try {
frame $wpath.testpkg-frame
} on error {msg opts} {
error "testpkg: Provided widget path: $wpath is invalid.\n$msg"
}

Or, you just go an create the 'frame' and let any errors propagate back >>normally.

I guess that would work, but sounds like trading six for half a dozen
to me. My way also works. Or is there something really wrong with it?

It is unnecessarially confusing trying to suss out what you are doing
with the splits and lranges for something that you don't need to do.
Just use the user's path, and let it succeed or error out.

One of the reasons for the addition of namespaces to Tcl was to
prevent name conflicts within plural packages that each wanted to use
the same name for part of their operation.

Do you not, often, create more than one "frame" or "button" or even
more than one single "text" widget? If you are thinking of this as >>possibly becoming an official 'widget' one day, then you have consider
a broader usage than what you believe your own usage might be. Someone >>else very well may want sixteen of these widgets across eight different >>toplevel windows all at the same time.

OK, maybe that is a risk. So instead of creating a 'testpkg' namespace,
I guess I will create a "testpkg_[clock milliseconds]" namespace. Do we
have a deal? :-)

If you want an object, then just create it as an object.

testpkg2 directory:

$ ls -1 testpkg2
pkgIndex.tcl
testpkg2.tcl

Contents of pkgIndex.tcl (created by "pkg_mkIndex ."):

$ cat testpkg2/pkgIndex.tcl
# Tcl package index file, version 1.1
# This file is generated by the "pkg_mkIndex" command
# and sourced either when an application starts up or
# by a "package unknown" script. It invokes the
# "package ifneeded" command to set up package-related
# information so that packages will be loaded automatically
# in response to "package require" commands. When this
# script is sourced, the variable $dir must contain the
# full path name of this file's directory.

package ifneeded testpkg2 1.0 [list source [file join $dir testpkg2.tcl]]

Contents of testpkg2.tcl

$ cat testpkg2/testpkg2.tcl
package requir Tk
package require TclOO

namespace eval testpkg2 {
oo::class create testpkg2 {

constructor {wpath} {
puts stderr "testpkg->constructor: my namespace is [namespace current]"
frame $wpath -height 100 -width 20
pack $wpath -fill both -expand 1
set fb $wpath.filelistbox
text $fb
$fb configure -font {Freesans 14} -height 2 -width 20
pack $fb -fill both -expand 1
$fb insert end "This is a test.\nLine 2."
}

# An extra 'method' as an example
method whoami {} {
puts stderr "I am object [self object] using namespace [namespace current]"
}

}
namespace export testpkg2
}

package provide testpkg2 1.0

Note, the "namespace export testpkg2" line above is what enables
importing the "create proc" for the object (technically the 'class').


Interactive session using the 'object' (well... technically, the
'class' as it is itself 'creating objects'):

Load a wish:

$ rlwrap wish

Setup auto_path

% lappend auto_path .
/usr/lib64/tcl8.6 /usr/lib64 /usr/lib /usr/lib64/tk8.6 /usr/lib64/tk8.6/ttk .

Package require the 'testpkg2' package:

% package require testpkg2
1.0

Perform the namespace import to make ::testpkg2::testpkg2 callable as
just "testpkg2":

% namespace import testpkg2::*

Create a new toplevel to hold a first instance of the widget:

% toplevel .t1
.t1

Create a 'widget' in the new toplevel, giving the widget a name of "myobjname":

% testpkg2 create myobjname .t1.tp2
testpkg->constructor: my namespace is ::oo::Obj22
::myobjname

Ask the 'widget' who it is (i.e., calling the example method). This is
how you'd communcate those "runtime" things to the widget, just with
different method names to do the things you want to do to it at
runtime:

% myobjname whoami
I am object ::myobjname using namespace ::oo::Obj22

Create a second toplevel:

% toplevel .t2
.t2

Create another (independent) widget in the second toplevel, this time
letting TclOO assign an object name:

% testpkg2 new .t2.tp2
testpkg->constructor: my namespace is ::oo::Obj23
::oo::Obj23

Ask the second widget who it is:

% ::oo::Obj23 whoami
I am object ::oo::Obj23 using namespace ::oo::Obj23
%

Two separate objects, each with their own private namespaces (for their variables/data/settings/state). Note the different namespace names
output by the puts line in the constructor when each was created.

And, if you go through this exercise above, you'll end up with the
default . window that wish creates, and two additional toplevels, each
with one copy of the 'widget' inside.
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From Newsgroup: comp.lang.tcl

For widgets consider using a meta framework. I use Snit but there are
others based on TclOO. Small learning curve but saves a lot of code you
would have to write yourself (for example, composing, Tk option database)


On 3/31/2024 10:47 AM, Luc wrote:

I'm trying to make a package that is meant to be used as a widget.
This prototype is called testpkg. Here are the files:

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

On Mon, 1 Apr 2024 10:57:24 +0530, Ashok wrote:

For widgets consider using a meta framework. I use Snit but there are
others based on TclOO. Small learning curve but saves a lot of code you >would have to write yourself (for example, composing, Tk option database)

I've no idea what a meta framework is. I suppose you mean this?

https://core.tcl-lang.org/tcllib/doc/tcllib-1-18/embedded/www/tcllib/files/modules/tool/tool.html

It seems it requires 8.6.

My current code will work as far back as 8.4, possibly 8.3 or maybe
even 8.0. I am very fond of backwards compatibility.
--
Luc

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

Luc <luc@sep.invalid> wrote:

On Mon, 1 Apr 2024 10:57:24 +0530, Ashok wrote:

For widgets consider using a meta framework. I use Snit but there
are others based on TclOO. Small learning curve but saves a lot of
code you would have to write yourself (for example, composing, Tk
option database)

I've no idea what a meta framework is. I suppose you mean this?

https://core.tcl-lang.org/tcllib/doc/tcllib-1-18/embedded/www/tcllib/files/modules/tool/tool.html

No, Ashok means what he said, "Snit" [1].

Which provides (among other things) a framework for building megawidgets
[2] [3],

It seems it requires 8.6.

My current code will work as far back as 8.4, possibly 8.3 or maybe
even 8.0. I am very fond of backwards compatibility.

Which is fine, but you will also lose access to a lot of newer things
that will make the process a lot easier.


[1] https://core.tcl-lang.org/tcllib/doc/tcllib-1-18/embedded/www/tcllib/files/modules/snit/snit.html
https://wiki.tcl-lang.org/page/Snit%27s+Not+Incr+Tcl

[2] https://wiki.tcl-lang.org/page/megawidget

[3] https://wiki.tcl-lang.org/page/What+is+a+Megawidget
--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

On Mon, 1 Apr 2024 18:45:16 -0000 (UTC), Rich wrote:

My current code will work as far back as 8.4, possibly 8.3 or maybe
even 8.0. I am very fond of backwards compatibility.

Which is fine, but you will also lose access to a lot of newer things
that will make the process a lot easier.

"make the process a lot easier" sounds like a big red flag to me.

A lot easier for whom? For the end user? Maybe. Maybe not.

What if they are stuck with an old OS or Tcl/Tk version that doesn't have
snit or TclOO? Will snit or TclOO be "a lot easier" for that kind of user
too?

Do you by any chance remember that I found I can't build Tk 8.6.13 or
later on my Debian 9 machine because it requires an X library version
that I don't have and cannot installe due to the cascading effect of dependencies?
--
Luc

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

Luc <luc@sep.invalid> wrote:

On Mon, 1 Apr 2024 18:45:16 -0000 (UTC), Rich wrote:

My current code will work as far back as 8.4, possibly 8.3 or maybe
even 8.0. I am very fond of backwards compatibility.

Which is fine, but you will also lose access to a lot of newer things
that will make the process a lot easier.

"make the process a lot easier" sounds like a big red flag to me.

A lot easier for whom? For the end user? Maybe. Maybe not.

A lot easier for you. Otherwise you'll have to provide all the extra
scaffold code to make your new widget act like Tk coders expect widgets
to act.

What if they are stuck with an old OS or Tcl/Tk version that doesn't have snit or TclOO? Will snit or TclOO be "a lot easier" for that kind of user too?

There is (or at least there was) a snit backport for 8.3.4:

https://wiki.tcl-lang.org/page/Snit+under+Tcl%2FTK+8%2E3

And this is stated on the main Snit page (https://wiki.tcl-lang.org/page/Snit%27s+Not+Incr+Tcl?R=0&O=Snit&W=):

As of 2010, Tcllib ships both Tcl-8.5-depending Snit v2.3.1 and
Snit 1.x that works with Tcl 8.3 and 8.4.

So there indeed is a Snit that works back to 8.3. However if you want
things to work even further back, well, then you'll have to code for
yourself some of the things Snit provides as assistance.

Do you by any chance remember that I found I can't build Tk 8.6.13 or
later on my Debian 9 machine because it requires an X library version
that I don't have and cannot installe due to the cascading effect of dependencies?

Vaguely. Was there some reason you had to stick with Debian 9 and
can't upgrade the whole install? Granted, I've got two systems with
older installs on them myself that are 'stuck in the past' largely
because I've simply not gotten around to upgrading their Slackware
installs. But that is totally my own fault for not having upgraded
them.

--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

On 4/1/2024 3:31 PM, Rich wrote:

Luc <luc@sep.invalid> wrote:

On Mon, 1 Apr 2024 18:45:16 -0000 (UTC), Rich wrote:

My current code will work as far back as 8.4, possibly 8.3 or maybe
even 8.0. I am very fond of backwards compatibility.

Which is fine, but you will also lose access to a lot of newer things
that will make the process a lot easier.

"make the process a lot easier" sounds like a big red flag to me.

A lot easier for whom? For the end user? Maybe. Maybe not.

A lot easier for you. Otherwise you'll have to provide all the extra scaffold code to make your new widget act like Tk coders expect widgets
to act.

What if they are stuck with an old OS or Tcl/Tk version that doesn't have
snit or TclOO? Will snit or TclOO be "a lot easier" for that kind of user
too?

There is (or at least there was) a snit backport for 8.3.4:

https://wiki.tcl-lang.org/page/Snit+under+Tcl%2FTK+8%2E3

And this is stated on the main Snit page (https://wiki.tcl-lang.org/page/Snit%27s+Not+Incr+Tcl?R=0&O=Snit&W=):

As of 2010, Tcllib ships both Tcl-8.5-depending Snit v2.3.1 and
Snit 1.x that works with Tcl 8.3 and 8.4.

So there indeed is a Snit that works back to 8.3. However if you want
things to work even further back, well, then you'll have to code for
yourself some of the things Snit provides as assistance.

Do you by any chance remember that I found I can't build Tk 8.6.13 or
later on my Debian 9 machine because it requires an X library version
that I don't have and cannot installe due to the cascading effect of
dependencies?

Vaguely. Was there some reason you had to stick with Debian 9 and
can't upgrade the whole install? Granted, I've got two systems with
older installs on them myself that are 'stuck in the past' largely
because I've simply not gotten around to upgrading their Slackware
installs. But that is totally my own fault for not having upgraded
them.

I solve the different versions by creating starpaks where I build a single file tcl/tk executable, often starting with one of Ashok's tclkits.

I include all the library packages I need as well as any other commands I want available w/o having to load them separately. Then I use the starpack as if it were a wish executable giving it the name of a script file to execute as arg one.

These all can run side by side on systems with older tcl's as the default w/o affecting them.



--- Synchronet 3.20a-Linux NewsLink 1.114

From Newsgroup: comp.lang.tcl

On Mon, 1 Apr 2024 22:31:28 -0000 (UTC), Rich wrote:

A lot easier for whom? For the end user? Maybe. Maybe not.

A lot easier for you. Otherwise you'll have to provide all the extra >scaffold code to make your new widget act like Tk coders expect widgets
to act.

OK. I've made these decisions:

1. Everything will be contained in its own namespace, including the
one proc.

2. I will maintain the rest of my original design. I can maybe get
it all done in two weeks because I've been busy with something else.

Learning Snit is definitely not easier for me. I've been avoiding it
for 20 years. I always thought it was way too complicated for little
to no benefit, at least within the scope of the things I normally do.
Learning Snit now (or TclOO) would set me back at least two or three
months. That's too long. I will look into it this year, but later and
taking my sweet, sweet time. And I am not really convinced I really
need it this time. I mean, do ALL third-party packages or megawidgets
out there use Snit? I doubt it.

3. I may rewrite my megawidget with Snit later. The code will be free
(BSD) as usual so anyone is welcome to change it if they like. I am
just afraid my code may not work well with geometry management, but
let's see.

Thank you for all the input.
--
Luc

--- Synchronet 3.20a-Linux NewsLink 1.114