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[/] [or1k/] [trunk/] [insight/] [itcl/] [INCOMPATIBLE] - Blame information for rev 1781

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1 578 markom
 
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As much as possible, I've tried to make itcl3.0 backward-compatible
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with earlier releases.  The class definition syntax has not changed
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at all from itcl2.2, and the old itcl1.x syntax is still supported.
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But you'll notice changes related to namespaces.  John Ousterhout
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adopted a slightly different namespace model for Tcl8.  The syntax
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of the "namespace" command is different, as well as the semantics
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for command/variable lookups and imports.  Also, John Ousterhout
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failed to adopt ensembles into the Tcl core, so itcl can't add
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functions like "info objects" and "info classes" into the usual "info"
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command.  These functions have been moved to a new "itcl::find" command.
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The [incr Widgets] package has changed quite a bit.  There are many
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new widgets, and some of the existing widgets were streamlined--some
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of the widget options were removed to improve performance.  For details,
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see the "CHANGES" file in the iwidgets3.0.0 directory.  Because there
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are a lot of changes, this distribution contains the iwidgets2.2.0
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package, which is backward-compatible with the existing [incr Widgets].
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Following is a quick summary of changes, to serve as a porting guide.
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----------------------------------|-------------------------------------
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 You have code like this...       | change to this...
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----------------------------------|-------------------------------------
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 namespace foo {...}              | namespace eval foo {...}
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                                  |
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 delete namespace foo             | namespace delete foo
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                                  |
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 info which -namespace $name      | if {![string match ::* $name]} {
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                                  |     set name [namespace current]::$name
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                                  | }
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                                  |
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 info context                     | namespace current
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                                  |
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 info objects ...                 | itcl::find objects ...
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                                  |
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 info classes ...                 | itcl::find classes ...
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                                  |
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 In itcl2.2, commands/classes     | In Tcl8.0, all commands/classes that
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 could be found in any namespace  | are not in the global namespace must
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 in a hierarchy.  So within a     | be qualified.  For example, the
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 namespace like "iwidgets" you    | "iwidgets" namespace has a bunch of
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 could use simple names like:     | classes within it.  You must always
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                                  | refer to these classes with qualified
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                                  | names, like this:
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                                  |
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 Labeledwidget::alignlabels ...   | iwidgets::Labeledwidget::alignlabels ...
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 Pane #auto                       | iwidgets::Pane #auto
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                                  |
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                                  |
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 In itcl2.2, the "global"         | In Tcl8.0, the "variable" command is
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 command was used to access       | used to access variables in a namespace:
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 variables in a namespace:        |
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                                  |
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   namespace foo {                | namespace eval foo {
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       variable x 0               |     variable x 0
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       proc example {} {          |     proc example {} {
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           global x               |         variable x
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           return $x              |         return $x
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       }                          |     }
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   }                              | }
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                                  |
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                                  |
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 public itk_component add...      | itk_component add ...
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 protected itk_component add...   | itk_component add -protected ...
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 private itk_component add...     | itk_component add -private ...
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                                  |
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                                  |
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 OTHER DIFFERENCES
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------------------------------------------------------------------------
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- You can now use instance variables (along with the usual common
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  variables) with the "scope" command.  Thus, you're no longer forced
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  to use the trick with a common array like:  [scope modes($this)]
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- All widget/mega-widget access commands (e.g., ".foo.bar") are
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  installed in the global namespace.  Therefore, they can be accessed
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  from any namespace context.
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- The [incr Widgets] package used to be loaded by default.  You must
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  now use the "package require" command to load it explicitly:
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    package require Iwidgets              <-- loads the lastest (iwidgets3.0.0)
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    package require -exact Iwidgets 2.2   <-- loads the older release
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- Command/variable names are now reported with fully-qualified names
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  in "info" inquiries and in error messages.
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- No public/protected/private declarations outside of class definitions
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- The "scope" command used to be more or less the same as the "code"
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  command.  In itcl3.x, "scope" is only for variables, and if a variable
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  is not recognized, you'll get an error.
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- The "code" command used to return a value like "@scope ...".  It now
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  returns "namespace inscope ...", to be compatible with Tcl8.
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- The prototypes for Itcl_RegisterC and Itcl_FindC have changed.  You
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  can now include ClientData when you register C functions.  Also, there
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  is a new Itcl_RegisterObjC function for (objc,objv)-style command
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  handlers.

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