TclTk WorkShop July 1996

These are a summary of the notes I took at the Tcl Workshop in Monterey July 10-13 with regard to Tcl Futures and Development Projects

Errors and Omissions mine.

This is what The conference t-shirt looks like.

Tcl Futures and Status

Update on Tcl Project- John Ousterhout

What did over Last Year

• Tcl7.5 and Tk4.1
  • Mac and PC ports
  • Dynamic loading and packages - big Impact expected on installation
  • New IO system , socket support, Cross Platform Issues
  • Multiple Interpreters, Safe-Tcl
  • Grid Geometry Manager(Tk) - Much better model for GeomMgr
  • New clock command
  • Performance improvements in text Tags
• First Alpha Release SpecTcl/SpecJava ("The Evil Twin")
• Netscape Plugin
• WebEdit Authoring Tool for HTML - encourage to Release soon
• Major Progress on Tcl Compiler

What didn't do that said would do

• FCS of SpecTcl (needs grid revision)
• NameSpaces (part of compiler)
• Internationalisation
• MegaWidgets
• Image Improvements - Memory utilisation and avoid dithering

People

• PC And Mac: Ray Johnson, Syd Polk, Scott Stanton, Colin Stevens
• Netscape Plugin, Security, I/O: Jacob Levy
• SpecTcl: Ken Corey, Stephen Uhler
• Compiler: Brian Lewis
• Web Authoring Tools: Brent Welch
• Mkting/Business Planning: Jay Backstrand
• Plus various Summer Interns

Release Plans

• Tcl7.5p1 and Tk4.1p1 - bug fixes to Tcl7.5 and Tk4.1
• Tcl7.6 and Tk4.2 - Patches + Grid Rev SpecTcl.
• Tcl7.6plug and Tk4.2plug - embedding and other features for Netscape plugin.
• Tcl7.7 and Tk4.3 - Native Look and Feel on PC and Mac (A Big release).
• Tcl8.0 and Tk?? - Bytecode compiler

• Alpha and Beta releases of above may overlap rather than pass thru all of above sequentially.

Tcl7.6 + Tk4.2

• Major grid cmd Rev - needed for SpecTcl
• C API change for channel drivers - eliminate Tcl_File struct use.
• No other changes except bug fixes (same as patch rel)
• Goal: Beta rel in August, Final Release Sept
• Question : MegaWidget Support in this rel - Probably not, increased risk.

Tcl7.6plug + Tk4.2plug

• Provide Features for Netscape Plugin
  • Application embedding in tk windows and embedding Tk toplevel window in provided wdwId.

        frame .x -container 1
        toplevel .t -use [winfo id .x.y]
        wish -use 0x6800004	
    

  • Focus revision, C API only
  • Safe-Tk, Security Models
• Work already provided in plugIn Binaries
• No Source ref till tcl7.7/tk4.3
• PlugIn Sources probably not freely available, Support platforms using binary ports.

Tcl7.7 + Tk4.3

• Native Widgets on PC and Mac - same scripting interface
• Config options a union superset of those available on all machines, Unsupported options silently ignored.
• New Menu Mechanism
  • Menubars implement with new menu widgets
  • new -menu option for toplevel windows - given menu widget will attach to this toplevel outside Tk widget hierarchy
  • Tear off menus are clones (consistancy guaranteed)
  • Can use same menu in several places - shared menus
  • Hide Tear off entries
• New Font mechanism
  • Will always get a font returned tho may not be exactly what asked for
  • Will define a small set of standard 'portable' font names
  • Provide official 2 level C API to fonts: I18n happen under this API

    label.l -font {times 12 bold}
    font create title -family Helvetica -size 24 -weight bold
    label .l2 -font title
    font configure title -size 36 ;# reconfigure font and do widget update 
    

  • Want to lose tearoff menus indexed as item 0 from menu Namespace.
• Virtual Bindings and Event Generation
  • define virtual names for events and bind them to platform specific actions.
  • Generate synthetic (virtual or non) events

    event add <<Paste>> <Control-v>
    bind entry <<Paste>> { ...}
    event generate .t <Button-Press> -button 1 -x 47 -y 18
    

• Standard Dialogs - FileSelectionBox (Read and Write)
• Portable File Commands: rm, mv, mkdir, rmdir, ... equivalents
• Binary I/O Support
  • Read/Write Blocks of Data (stored behind scenes in tcl)
  • Insert/extract fields of blocks
  • Copy between channels ("unsupported0" )
• Other possible additions
  • MegaWidgets
  • Image Revision
    • No dithering
    • Memory footprint
    • Channel support
  • More text Improvements - smooth scrolling, Handle long lines better
• Schedule Estimate:
  • First Alpha rel Oct/Nov 96 (then 6 months to final)
  • Final Release Q2 97 (i.e before next workshop)

Tcl8.0

• ByteCode Compiler
• New Object system for internal data representation
• New C API's for Command Procedures, many other Tcl lib procedures
• All new API's where currently reference strings
• Old interface still supported but 'slow' - not faster than now, maybe slower due to internal conversions to Tcl_Object
• NameSpaces
• Compiler will be free
• Possible changes in semantics
  • Alpha release will be most aggressive then will progressively relieve in later releases in reponse to user feedback.
  • More aggressive list syntax checking, conversion immediately use lappend, lindex
  • Changes to error messages, errorInfo (provide line numbers)
  • Eliminate current possibility of multiple substitutions in expressions

    set x {$y+2}
    expr $x * 4 ;# equiv $y + 2 * 4 
    

  • Retain string values for comparisons so do expected thing

    if { "0y" < "0x12" } { ;# unexpectedly succeeds }
    

• Schedule: Estimate
  • First alpha Oct 1996
  • Final Rel Q2 1997
  • Additional Speedups in later release

  • Alpha may release before tcl7.7 release
  • Final release will include tcl7.7 releases.
  • if tcl8.0 available earlier will not release tcl7.7

Other Projects

• SpecTcl and SpecJava
• WebEdit and MicroScripting
  • Edit Web Pages - WYSIWYG with WebEdit
  • Insert Tcl/Tk at various places
  • Scripts fire at interesting times
    • Site Config (Page installation)
    • Page Fetch (CGI)
    • on client machine (plugin)
  • Pull together WebEdit, SpecTcl, PlugIn, Tcl
• Safe-Tcl
  • Better Tk support, socket communication
  • Interesting Security Policies
  • Add Authentication and MD5

Making Money

• Sources for the core will always be free
• Compiler will be free
• Prebuilt Binaries for sale on First Virtual InfoHaus
  • Currently Solaris only
  • Add SunOs, HP, SGI,etc
  • Can Add own products there also
  • Not much business to date
    "Made the sources too easy to install and build but we think we know how to fix that"
• Netscape Plugin
  • Free for personal and educational use
  • Corporate use require license after 90 days
• SpecTcl/SpecJava, WebEdit
  • May be free initially
  • Eventually cost (as per plugin)
• Mac and PC binaries may be avail at cost from "Big Release" (Tcl7.7 and Tk4.3). Otherwise if want them will have to build yourself from freely available source.
• Probable Redistribution Issues (not addressed yet)
• Runtime (free) vs Development tool (cost)
• Others may want to setup binary distribution mechanisms built from available source - there is nothing they can or will do to hinder that.

Publicity developments

• Official Tcl/Tk Logo (this is a screen scraped image)
  • Get Feedback at workshop
  • Available in several sizes, formats (will provide gifs)
  • Freely use in Tcl Extensions, Apps
• Cover story on Sun Home Page. Story runs till End of July returns in early August.
• Press release for Netscape plugin, Ports
• Alliances anyone ??
• Must be seen as augmenting/enhancing Java not competing with it.
• Need More books
  • Have 3 on Tcl
  • One on expect
  • One more on extensions is coming (O'Reilly)
• Most importantly also Had T-shirts - lots of T-Shirts, Variety of size and colors (grey, white and red)

Other

SpecTcl - Why not Use

• Not Usable
• Not Faster than by hand
• Not native GUI
• Can't convert existing code
• Unstable
• Lack of Features

Internationalisation Difficult areas

• Font resolution
• regexp handling
• tranducing unicode to external form
• Choosing and defining level of I18N support

Tcl/Tk plugin - Jacob Levy

• Write in Tcl not C or HTML
• Tcl Code is portable
• Safe Execution environment "Padded Cell" environment using Safe-Tcl, trusted Master Interpreter.
• Infinite extensibility
• Dynamic loading into Plugin

• Minimal scripting differences from base Tcl/Tk
• New Variables tcl_pluginVersion, ...,
  embedded args passed from html page to plugin embed_args array

How Use

• Create Web Page in HTML, use Embed tag specifying Tcl script
• Create Tcl Program that Web Server can find in response to the Tag
• Plugin executes and reads/runs Tcl Code.

Status

• Alpha releases for Solaris, Win32 and Mac. Will make binaries for any platform that supports Navigator 3.0 and that there is a requirement for (AIX, HP/UX, Linux, .. )
• Not Feature Complete
• Currently limited to Navigator 3.0

Future Extensions

• Navigator 2.0, Internet Explorer - Anything supporting Plugin interface
• SunOS and MSW3.11 ports
• Java And JavaScript Linking
• Fetching URLS, Driving interacting with Browser
• Authentication
• Security Policies
• Dynaic loading into plugin
• Remote Servers
• ActiveX, OCX,s, Nashville
• Suggestions Welcomed

In Search of the Perfect MegaWidget- Stephen Uhler

These may be wanted for

• Compound Widgets (ComboBox - Text entry with droplist)
• Change Look/behaviour of existing widgets (text to html widget)
• Remove functionality from existing widgets
• Change Layouts of existing widgets e.g a space saving Scale Widget

MegaWidget Solution

• Change Core to provide mechanism for complete Megawidget capability
• Is NOT addressing NameSpace Facility, framework for Widget construction

Properties

• Command Interface - same as Builtin Widget

      e.g. widget .foo
  	 .foo configure ...
           .foo cget ..
  	 .foo sun-command ?args?
      

• Behaviour - winfo access (exists, class, width, height), Option Database, Focus handling)
• Bindings - User attached to megaWidget handled as would expect... (only caveat need use %X, %W substitution in action code )

Changes required

• frame - add a -command option making the frame a megawidget and specifying code to be run when the widget command is executed. Provide frame subcommand really that causes args to be passed to the actual frame widget

      frame .mega -class Mega -command {mega .mega}
      proc mega {name args} {
  	$name really configure ...	;# handle frame args
  	# other processing for sub widgets or whatever
      }
  

• Event Propagation and translation
  • Some events propagated to enclosing container
  • detects if widget is in a megaWidget container, resynthesises event and passes to container.
• Focus
  • Limit returned info to container rather than children
  • return outermost container that has focus. Provide options in focus command to get child of container.

Implementation

• New Flags in TkWdw structure IS_CONTAINER, IS_CONTAINED_IN
• Recursive event dispatch
• Event substitution
• New options on winfo and focus
• C API

Conclusion

• Most capabilities already in Tk
• Small changes in event and focus handling needed
• Added features for convenience
  • easy access to Tcl Code
  • MegaWidget Introspection

On the Fly Byte Compiler for Tcl - Brian Lewis

• Goals
  • Faster Interpreter
  • Smaller Memory Footprint
  • No Script API changes
• Preliminary results
  • Speedup 5-10 x
  • Code Size <= source size
  • Compile time : 0.2 - 2.3 times execution time
• Why isn't Tcl faster
  • Conversion of strings to other forms
  • Too many decisions at runtime
• Internal changes - Dual ported Object. Internal representation
  • String augmented by 'natural' internal representation
  • Representation and string are cache of each other - lazy computation
  • Representation controlled by a type description - extensible
  • Internal Object size is about 20 bytes plus size of string
  • Objects are heap allocated
  • 7 predefined Types : Int, double, bool, string, list, bytecode, cmdName (CommandName lookup), cache
  • Extension writers can define new types for their extensions

  typedef struct Tcl_Obj {
      int refCount;		/* when 0 object freed */
      char *string		/* String rep */
      Tcl_ObjType *typePtr;	/* reflects the objects type */
      union {
          int intValue;	/* a int rep */	
  	double dblValue;	/* a double rep */
  	VOID *otherValue;	/* Another type specific value */
  	struct {		/* value as two words (ints) */
  	    int field1;	
  	    int field2;	
  	} twoIntValue;
      } internalRep;
  } Tcl_Obj
  
  typedef struct Tcl_ObjType {
      char *name;		/* Name of the type - "int","list" */
      Tcl_FreeInternalRepProc *freeIntRepProc;
  			/* frees any storage for types internal rep */
      Tcl_DupInternalRepProc *dupIntRepProc;
  			/* Creates new obj as copy of existing */
      Tcl_UpdateStringProc *updateStringProc;
  			/* Updates string rep from internal rep */
      Tcl_SetFromAnyProc *setFromAnyProc;
  			/* converts old internal rep to this type */
  }
  

• ByteCode Interpreter
  • Emits bytecodes that are interpreted
  • 64 Instructions, avoid reparsing and runtime lookup
  • Evaluation stack - args and expressions
  • Basic Operation
    • Compute and push args
    • invokeStk to call cmd proc
    • push Result
    • Only gives 2x speed imnprovement
  • CompileProcs
    • Specially compiled high payoff commands
    • set commands: read vs asignb, scalar vs array
    • while cmd: emist jumps, inline compile, test, body
    • 6 procs total : set, expr, incr, while, if, for
  • Assignment of Stack frame slots to local variables runtime locals -> hashTable > 13x speedup
• Status
  • No Tk yet
  • Finished :
    • Object Framework, conversion to Object types
    • Compile Procs
    • Free slots for local variables
    • expressions - no double eval
• Performance (speedup)

  	lindex eolist		44.6x
  	linsert eolist		5.2x
  	iterative factorial	14x
  	Mortgage Payment app	19x
  	one-way crypto		5.5x
  

• Vs other Languages - other:tcl8.0

  	tcl7.5		0.073
  	Perl5		0.7
  	Tcl8.0		1.0
  	Java		4.2
  	C	       40		
  

• Implications for Tcl Code
  • Use Lists (faster than arrays now)
  • Comments are Free
  • lists are aggressively parsed- may find errors in list structure earlier than previously
  • Error Tracebacks are liable to be different
  • To maximise performance :
    • Avoid computing variable names
    • place global commands at top of procedure
    • if redefine core commands do it at program start
    • Extension writers use Tcl_Objects
• Future Work
  • First alpha Release will be in Tcl8.0 (Oct ??)
  • Compilation of further key commands as inline procs
  • Addition of Tcl Namespaces

Tcl Team HotList

• Compiler
• Safe Tcl/Tk
• Netscape Plugin
• Native Platform Support (Widgets, Fonts, etc)
• Image Improvements
• Binary I/O
• MegaWidget Support
• NameSpace Support
• Internationalisation
• Debugger
• WebEdit (WYSIWYG HTML editor) and Microscripting
• SpecTcl/SpecJava Dialog Builder
• Profiler

Suggestions for Development Areas

Tcl

• Binary I/O - support binary data same as does strings now
• Thread Safeness
• Plug and Play Loadable extensions
• "-warn" lint like syntax checking

• examples in Doc/Man Pages
• Doc on Internal Architecture - channels, Notifier, ...

• Tcl_InterpCreate option to not load init.tcl
• Minimal Core and loadable features (for embedding)

• Batch Compile Mechanism
• Priority Groups in event Loop
• shell Features into tclsh - tclsh a better interactive shell
• tclsh event driven
• Tcl CookBook - already available http://www.cis.rl.ac.uk/proj/TclTk/)

Tk

• Support more Image Formats
  • jpeg
  • png
  • xpm (already done (Tix))
  • bmp
  • pict
• 2 Way OCX support - Create and drive OCX's
• Event Logging
• State option on all Widgets (ability disable scrollbar/canvas)
• Traces On Widget Options
• postscript command for Text Widget
• Incremental Image Loading
• Tagging Widgets - widget grouping

• Selective removal of bindings
• bind tag inheritance or widget bindings init script
• Graphical interface to manage extensions
• Widget Command Registry
• input/export rtf
• Support existing VBX's (16 bit)
• C API to Canvas Widget

Other Interesting Work (that I captured Notes on)

Tcl Web Tools - Stephen Uhler

• Layered HTML Library - its easy to add HTML support to a Tk app
• 4 layers of implementation
  • Html_Parse - maps HTML onto Tcl commands, applies Tcl command to each HTML tag, Possible commands to validate URLS, steal Images, Render.
  • Html_Render - display Html in text widget, one possible function applied by Html_Parse.
  • Tag Specific Helper Functions (support own tags )
  • Link, Image and Form Hooks.

DPTcl- Gerald Lester

Neoscript - Karl Lehenbauer

• Save arrays to dbm files
• Talk to SQL Database
• Safe Interpreter environments
• embed tcl escapes in html pages
• Conveniences: Counters, Form generation, Table wrappers, ..

SWIG - David Beazley

TKsh - Jeffrey Korn

CGI programming with Tcl - Don Libes

Don opened this talk saying: I am going to refute the assertion made by Adam Sah in the previous talk (and John Ousterhout, yesterday) when they said: CGI scripting is too hard. While preparing this talk, I looked around for a short statement about CGI and why people find it hard. I found this one on HTML - it's close enough...

Slide title: What is this crap?

• If HTML had been turned in for a human factors class, it would have gotten an F.
  - Eric Schmidt, Sun

Slide title: My rating: D

• Hey, it does work after all.
• Kind of.

The talk described how to generate HTML from Tcl scripts. Several examples of CGI scripts in Tcl were shown - they were short and readable. Using the idea of an FAQ as an example, Don demonstrated that it is useful to generate static pages as well. Using these approaches, problems such as maintenance of URLs and translation between different formats become trivial.

Don described a freely-available Tcl library to support this work. See Don Libes and Writing CGI scripts in Tcl.

Plans/Directions for Contrib Archive - Karl Lehenbauer

• Enable People registry allowing you to add yourself if interested, Manage your own packages, uploads, Support etc...
• Compatibility matrices for extensions
• Ratings of Packages and comment storage
• Multiple indexes of Archive as well as searching (hypertcl reactivate or reproduce)
• Newsletter (electronic)
• Ftp : Keep fairly flat simple structure and index/Search from Web Pages.
• SiteMaps
• Nodes and Zooms
• Man Pages in html
• Pull out or separate ReadMes for provided Packages
• Unpack packages and provide WAIS indexing into their contents

TeamRooms - Mark Roseman

Caubweb - John LoVerso

Tk Interoperability Conference

Tk in other Languages (e.g. Perl, Python, Scheme)

Initial major concern was embedding of Tk in other languages but that seems to be well enough addressed currently with some relatively minor problems and slightly ugly hacks (according to the Perl, Python people attending). The architecture being built for bytecode compiler should provide remaining hooks and make porting integration process much easier. This turns out to be a superset of the Perl wishlist and appears also support Python and Scheme to the level required.

Tcl and Objects

[incr Tcl] supports its OO extension by adding namespace support to (a modified version of) the Tcl Core. This is something he needs to get out of. Namespaces will be supported in Tcl with the compiler release but its probable that a lighter weight hook mechanism in the right places is what is needed to provide a vehicle for Object extensions (e.g Namespaces and OOP separately) without needing to beat on Core code. This minimal hookset needs to be identified (features and geography) and provided simply and rapidly (Michael McLennan undertook to follow through on this).

Tcls notion of namespaces will probably be much simplified from iTcls: disallowing nested namespaces (i.e limit to local or global) or allow nesting but disallow shared namespaces....

Portability across Platforms

Many Issues such as Native Look and Feel, Printing i/f, Std MegaWidget Set, Font Abstraction, Portable filesystem access, Portability of extension code. Many of these are already addressed: e.g. Menus, Fonts, Colors, Virtual Events, Native Widgets and provision of Some Common Dialogs. Areas that are in the process of being cleared up include FileManipulation commands and Cursors.

Areas that are felt to be important but that are currently not scheduled include Internationalisation, Common C Extensions API (it was felt that this would evolve naturally as the ports are worked on), Native Printing support, Common Drag and Drop API, OLE/ActiveX embedding on MSWindows and some interface for a help system (both balloon style help and access to external help viewer/data).

Thread Support.

A small but vociferous minority insisted on some form of thread support being an important consideration for Tcl even if only as a checkbox item. This evolved to a realisation that Thread Safety (ability to run multiple interps in multiple separate threads without collisions) was probably the minimal desirable and maximum possible. Its unclear who would do this as the Core Tcl team already has more higher priority items than it can handle. A Tcl community contribution is probably the only way this will happen.

Other

Theres probably a need for a list of Items that the contrib community could provide and some forum for provision of and discussion of specifications for these things.
Once again for any contrib work to be included in the core it maximises its chances if it:

• Follows the Tcl coding conventions
• Has Man Pages provided in a form consistant with the existingt ones
• Provides test suites and test scripts
• has been tested and passes its test suite
• has been tested that it doesn't break anything in the existing test suite