Announcing NSF 2.0b5

 
Dear Community,

Since releasing 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 enviroments
(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