[Tcl-bugs] [ tcl-Bugs-2965424 ] Tcl_OOInitStubs has no version parameter

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Bugs item #2965424, was opened at 2010-03-08 14:08
Message generated for change (Comment added) made by nijtmans
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Category: 35. TclOO Package
Group: development: 8.6b1.1
Status: Open
Resolution: None
Priority: 7
Private: No
Submitted By: Jan Nijtmans (nijtmans)
Assigned to: Donal K. Fellows (dkf)
Summary: Tcl_OOInitStubs has no version parameter

Initial Comment:
Compare the following:
   Tcl_InitStubs(interp, "8.5", 0)
with
   Tcl_OOInitStubs(interp)

The version parameter of XX_InitStubs means the
lowest version supported by this extension. However,
in TclOO this value is already filled in being TCLOO_VERSION,
which is the "compiled-against" version.

The problem with this is, when someone compiles an extension
using TCLOO_VERSION = "0.6.3", but runs it with Tcl 8.6b1,
the XXInitStubs call will  fail, even though it should run perfectly.

There is a difference between the "lowest supported version",
and the "compiled against" version. It should be possible to
compile a TclOO extesion against TclOO 0.6.3 and run it
using TclOO 0.6.2: As long as no 0.6.3-specific features are
used (and the extension developer is the only one knowing
this), everything should be fine.

More specific, I suggest to change:
#define Tcl_OOInitStubs(interp) \
	Tcl_PkgRequire((interp),"TclOO",TCLOO_VERSION,0)
to
#define Tcl_OOInitStubs(interp, version) \
	Tcl_PkgRequire((interp),"TclOO", version, 0)
Maybe we should even have an "exact'
parameter, just as the other *StubInit functions. 

This needs to be coordinated with Itcl and tdbc,
because it introduces a source incompatiblility!
Binary compatibility is not affected, except for
the "exact" parameter!

B.T.W: Tdbc_InitStubs has the same problem, but
Itcl_InitStubs is O.K.
B.T.W.: Personally, I don't mind very much about the
"exact' parameter, but I could imagine the desire
to keep it exactly the same as Tcl.

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>Comment By: Jan Nijtmans (nijtmans)
Date: 2010-05-31 10:07

Message:
Thanks for your reaction.

Where can I find more about this? Is it ever discussed
anywhere? (I happen to disagree, but I know that more
people in the TCT vary in opinion about this).

My view: Indeed, the package release version is different from
an ABI. But because Tcl promises to keep the ABI upwards
compatible in minor releases, there would never exist
different ABI versions for equal package versions. I
never saw an ABI version other than 0 anywhere.
So, yes, I would like to couple the ABI version to the
package version: Any ABI incompatible change should
lead to a new major package version. That's what
Tcl has done always, and extensions should do
the same.

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Comment By: Joe English (jenglish)
Date: 2010-05-30 19:15

Message:
For what it's worth, I believe the one-argument form XXX_InitStubs(interp);
is to be preferred for all new stubs-supplying extensions.  The
three-argument form XXX_InitStubs(interp, version, exact); is error-prone
and incorrectly couples the package release version to the ABI version.

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Comment By: Jan Nijtmans (nijtmans)
Date: 2010-03-08 14:56

Message:
OK, here is a new patch, being more strict in requiring 'exact' version
match.

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Comment By: Jan Nijtmans (nijtmans)
Date: 2010-03-08 14:43

Message:
In that, case, you can still use my patch, but set "exact' to 1. Then, at
least,
Tcl_OOInitStubs has the right signature.

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Comment By: Donal K. Fellows (dkf)
Date: 2010-03-08 14:38

Message:
I make no deep guarantees until version 1.0, which will correspond exactly
with Tcl 8.6.0

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Comment By: Jan Nijtmans (nijtmans)
Date: 2010-03-08 14:27

Message:
The proposed patch has the 'feature' that binary compatibility is
guaranteed, but source compatibility is affected. However,
TclOO extensions which are modified, immediately are
binary compatible with 'the right way'.

See the TODO in the patch.

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