[Xotcl] Announcement: Next Scripting Framework 2.0b5 available

[Gustaf Neumann]

Dear Community,

Since the last release of the the Next Scripting Framework
(NSF 2.0b3), we have received feedback from early adopters.
Many thanks for the helpful and the constructive comments!

This feedback triggered an internal discussion and led to 
revising
some earlier design decisions and naming conventions, 
especially
in NX. The new naming conventions improve the orthogonality and
the clarity of NX programs.

Since the release of 2.0b3, there have been more than 250 
commits to
our code repository. The implementation is very stable and 
has been
used for more than two years in production of our large-scale,
multi-threaded web environment inside NaviServer. Most of 
the changes
happened in NX and, therefore, on the NSF scripting level, 
without the
need to modify the NSF C layer. The implementation of XOTcl 
2 has
changed very little. The Next Scripting Framework was tested 
with Tcl
8.5.14 and Tcl 8.6.0 on Linux, Mac OS X, and in windows 
environments
(MinGW, VC11).

This beta-release is supposed to be the last release before
the final 2.0 is out, which should be soon.

Below are the most notable differences in 2.0b5 as compared to
2.0b3:

a) NX 2.0b3 used the following conventions to define methods for
    instances, object-specific methods and class-object specific
    methods:

      /cls/ method foo {args} {...}
      /obj/ method bar {args} {...}
      /cls/ class method baz {args} {...}

    Introspection was possible via (in the same order):

      /cls/ info methods
      /obj/ info methods
      /cls/ class info methods

    The problem with this convention is that e.g. "info methods"
    operates on different method records, depending on 
whether it is
    called on a class or on an object. This breaks a basic 
inheritance
    contract with the programmer: As nx::Class is a 
specialization of
    the most general class nx::Object, the same 
introspection operation
    (e.g., "info methods") should return e.g. 
object-specific methods
    for both class objects and ordinary, non-class objects.

    Therefore, we adopted the following more orthogonal
    conventions to define methods for instances and
    for object-specific methods

      /cls/ method foo {args} {...}
      /obj/ object method bar {args} {...}

    Introspection:

      /cls/ info methods
      /obj/ info object methods

    Note that we can now use the same mechanism to define
    or query object-specific methods on objects and classes.
    The same applies for aliases, forwards, mixins, and filters.

    The new convention imposes a little typing burden for 
the code
    writer, but reduces the potential ambiguity for the code 
reader,
    who is trying to understand what exactly "$x method FOO 
{args}
    {...}" means.

    For convenience, we provide two packages 
"nx::plain-object-method"
    and "nx::class-method" to switch to the old conventions. 
A verbose
    tracing mode can report usages to ease migration.


b) Parametrization:

    NX 2.0b3 followed the XOTcl conventions of registering 
by default
    same-named getter/setter methods for configuration 
parameters used
    in object creation. These getter/setter methods bloat 
the method
    interface and risk shadowing inherited methods, leading to
    unexpected behaviors for beginners.

    NX 2.0b5 adopts a Tk/itcl/... idiom by offering a 
cget/configure
    interface to objects as generic getters/setters. To obtain
    parameter-specific getters/setters (i.e., the old 
behavior), the
    flag "-accessor public|protected|private" can be set 
when defining
    properties and variables.

c) Further clean-ups of the introspection interface ("info").

    In order to streamline the interface further, we 
followed the idea
    to use "... info /plural word/" to obtain a set of 
handles, and
    then to make a separate call to retrieve the details. 
Therefore, we
    now provide ...

      /cls/ info methods
      /obj/ info object methods

      /cls/ info variables
      /obj/ info object variables

      /cls/ info slots
      /obj/ info object slots

      /cls/ info method parameters /methodName/
      /obj/ info object method parameters /methodName/

      /cls/ info configure parameters
      /obj/ info lookup configure parameters

    ... to return a list of handles. The result list can be 
filtered in
    each case by specifying a match pattern. Each result 
handle can
    then be used in a separate call to obtain details:

      /obj/ info method definition /methodHandle/
      /obj/ info variable definition /varHandle/
      /obj/ info parameter name /paramHandle/

    These are just a few examples.

    In NX 2.0b3, we had e.g. "... info parameter definitions 
..."
    leaving a beginner in the dark about the parameters actually
    meant. Also, the introspection interface made mixed use 
of plural
    and singular wordings for different purposes (e.g., 
retrieving
    collections and/or detailed information on one item).

Below is a more detailed summary of the changes.

The Next Scripting Framework 2.0b5 (containing NX and XOTcl 
2.0b5) can
be obtained from http://next-scripting.org/

Best regards
- Gustaf Neumann
- Stefan Sobernig

===============================================

Announcing NSF 2.0b5
*************************

Major changes relative to NSF 2.0b3 are (in addition of
the items (a), (b), and (c) above) are:

    * Additional Features:

      - Serializer:
        * Added flag -objmap to Serializer method deepSerialize
          to make serializer to provide mapping only for
          object names. This makes the serializer
          usable for object/class copying (-map is too coarse)
        * Made "ignore" method public
        * Due to the split between serializer and object
          system serializer, the "ignore" settings were lost

       - Allow explicit unsetting of -per-object flag in 
0-argument
     "-flag=value" notation (all built-in commands accepting 
this flag)

      - Better compatibility with XOTcl 1.*:

      - Added "/obj/ info name" (as alternative to
        "namespace tail [self]")

      - Test-suite: added summary with statistics

      - Traits: added property/variable inheritance

      - MongoDB
     - Added "nx::mongo::db drop collection /name/"
     - Returning status from "nx::mongo::db remove" as 
success (0 or 1)
     - Adjust to object interface
     - Reduce verbosity
     - Add error messages for slot lookup failures

     Updated MongoDB interface
     - Upgraded to c-driver 0.7.1
     - Zested with MongoDB 2.4.4-pre
     - New commands:
       * mongo::run
       * mongo::cursor::find
       * mongo::cursor::next
       * mongo::cursor::close
     - Adapted interface for c-driver 0.7.1 (e.g. new
           optional name for mongo::index)


    * Improved Code Quality:

      - Fixed functional bugs:
        * Copy did not copy aliases and ensemble methods
        * Automatic object destroy for half-baked objects
          (when e.g. configure raises an exception)
        * Handling of required configure parameters
          on later calls to "configure"
        * Fixed potential infinite loop in pattern matching for
      precedence lists
        * Handling of full-qualified name patterns
          for private slots
        * Invalidation of per-object parameter cache
       - on mixin changes and
       - on deletion/adding of per-object slots
        * Handle cyclical superclass/class dependencies 
during object
      system finalize
        * Fixed a bad interaction between Tcl's apply 
(pushing lambda
      frames) and the variable resolvers. The variable 
resolver was
      not able to resolve variables, while the command 
resolver was
      still working correctly.
        * Don't allow "method" to overwrite child objects

      - Fixed potential crashes:
        * Avoid crash on object destroy, when the same 
wrapper-less
          aliases was registered on more than one object/class
        * Fix crash on "nsf::my", when this is called with a 
single
          argument outside an object context (many thanks
          to Markus Moser for reporting)
        * Avoid crash in case NsfParameterGetCmd() is passed
          a plain value (without a parameter spec)
        * Fix potential crash in method caching when commands
          are renamed by Tcl (many thanks to Arthur Schreiber
          for reporting)

       - More code cleanup and refactoring

       - Released version runs all regression tests
         without memory leaks with Tcl 8.5.14 and
         Tcl 8.6.0

      - Build system:
        * Improved compatibility for windows compilations.  
NX can now
          be compiled under windows with the native window 
tool chain
          (VC11) and as well with MinGW (Many thanks to Stephan
          Adelsberger)
         * Update to latest TEA
     * Follow new naming convention for auto-tools
           (using configure.ac)
     * Fix compilation when DTrace is activated (missing
           parenthesis, many thanks to Victor Guerra for 
noticing)
     * Added compile macro NSF_STACKCHECK to provide stack
       monitoring/debugging (especially useful for multi-
           threaded programs, where stack is more limited)
     - Fix compilation when compiled without threads
           (many thanks for r.Zaumseil for noting this)

    * Improved documentation
      - Fixed typos, improve wordings
      - Updated tutorial and migration guide
      - Use slashes in generated syntax to distinguish
        between constants and placeholders.
        Example:
          /obj/ info method definition /methodName/

     * Extended regression tests

MORE INFO
   General and more detailed information about the
   Next Scripting Framework and its components can be
   found at http://next-scripting.org