The Black Box Toolkit

User's Guide

bbtk version 0.9.0 (15/10/2008)
Generated on : Nov 12, 2008
Eduardo Dávila, Laurent Guigues, Jean-Pierre Roux
CREATIS-LRMN, Centre de Recherche en Imagerie Médicale
CNRS UMR 5220, INSERM U620, INSA Lyon, Université Claude-Bernard Lyon 1

1  Introduction

1.1  What is bbtk ?

The Black Box Toolkit (bbtk) is a set of tools (C++ libraries and executables) providing a C++ framework for the definition of elementary processing units, called black boxes, and the definition and execution of processing chains made up of these black boxes.

1.1.1  The black box philosophy

The Answers Dictionary defines a black box as "A device or theoretical construct with known or specified performance characteristics but unknown or unspecified constituents and means of operation"
Wikipedia defines a black box as "any component in a system in which only the input and output characteristics are of interest, without regard to its internal mechanism or structure".
We should merge these definitions. : not only the inputs and outputs are of interest but also what the box does ! Hence, we would say that a black box is any documented component of a system, letting the user know what the box is supposed to do and how to use it but not how it does it.
The Black Box Toolkit provides a systematic framework to encapsulate (or "wrap") any existing C or C++ processing code into an object (a black box) having a generic symbolic interface, where
(Actually, genericity is achieved because the interface is symbolic. We let you think about this...)
Of course, symbolic data attached to a box may be queried : what are the inputs/outputs of the box ? what are their type ? their description ? etc. This allows automatic documentation of boxes.
The abstract definition of black boxes is the most basic aspect of The Black Box Toolkit architecture. Another key aspect is the groupement of black boxes into so called packages, which are dynamic libraries which can also be queried, in particular about the boxes they provide. The package structure then offers a mechanism which is like a 'plug-in' mechanism. The Black Box Toolkit provides the methods to load a package at run-time, and create instances of the boxes it contains.
These two mechanisms (black boxes and packages) then gives the way to:
Finally, these different components allow efficient :

1.1.2  bbtk components

The Black Box Toolkit includes :
The general architecture of The Black Box Toolkit is shown in figure .
Figure 1: The Black Box Toolkit architecture

1.2  Content of this guide

2  Getting started with bbStudio

2.1  The interface

Just run it, typing in a console bbStudio or clicking on its icon or its menu entry. You'll get something like in figure (the exact appearance of bbStudio is Operating System and bbtk version dependent).
At start, bbStudio opens with a very minimal 'How to use' in the middle. Don't forget to read it : it will vanish at the first mouse click.
Figure 2: The bbStudio Development environment interface at start time
The interface is divided into four parts : Files, Messages, Command, Help. It is written using the Advanced User Interface library of wxWidgets (a.k.a. AUI), whose 'docking manager' allows windows and toolbars to be floated/docked onto a frame. Feel free to resize/reposition any part you want. Your preferences will be kept next time you run again bbStudio.

2.1.1  'Files' part

It's the bbs script editor.
If you load a file holding a script, it will be displayed here, and you'll be able to modify it, to save it, to save-as it, to run it, using the lower toolbar (see figure )
Figure 3: The 'Files' lower tool bar

2.1.2  'Messages' part

Two kinds of messages will be output here:
System messages : produced by the kernel, in case of a user mistyping, or an execution error
Script messages : produced by the bbtk equivalent of printf or std::cout in user programs.

2.1.3  'Command' part

You can type here bbs commands which are executed on the fly. The buttons are shortcuts to usual commands.

2.1.4  'Help' part

The 'Help' part of bbStudio is used to browse the html help of The Black Box Toolkit.

2.2  Running Demos and Examples

In the 'Help' part (See figure ), select Examples link.
Figure 4: bbStudio 'Help' panel
You will get a list of examples (See figure ).
Note : due to an unfixed bug in Linux, you have to click on 'reload' to get it.
Figure 5: Examples list
Select wx::exampleSlider.
Figure 6: Html documentation of example 'exampleSlider'
You can see information on the example and the graphical representation of the workflow defined by the script (the elementary boxes that compose it, and their connections, see figure 6).
Click on [source], it will be loaded in the 'Files' part, within the script editor (See figure );
Figure 7: Source code of 'exampleSlider'
Run it, using the 'Files' toolbar (see figure 3)
You'll get something like in figure .
Figure 8: Execution of 'exampleSlider'
Feel free to move the slider, to check it actually works...
Just a few words on what you saw :

2.3  Online Help

Various levels or help are suplied by bbStudio.

2.3.1  Command line help

The 'working' area (the left one, as opposed to the 'help' area, on the right side) is composed of : one single line area (Command), at the bottom, in which you can enter your commands and a multiple line zone in which the Command interpreter prints out the result of your commands. Command line help for the black box scripting language (bbs) can be obtained in this zone (see ).

2.3.2  Guides

An html version of all the guides is browsable in the Help part of bbStudio.

2.3.3  Boxes Help

Lists of currently available boxes from installed packages

2.3.4  The Package Browser

The package browser is a standalone application which dynamically loads and queries the available packages. It is thus a smarter tool than the static html documentation. You can run it with the command bbPackageBrowser or in bbStudio using either the button of the 'Command' part or the menu entry 'Windows > Start Package Browser'. Remark that it may take some time to start because it loads all available packages at start. Its appearance is reproduced in figure .
Figure 11: The Package Browser
It allows you to find boxes using a multi-criteria filtering principle : The boxes listed are the one whose attributes match all the words entered in the 'Filter' part. You can get the whole description of a given box clicking on its name.
Warnings :
Attributes :

2.4  The Menu

At last, let's have a look at bbStudio menu.(See figure )
Figure 12: The bbStudio menu

3  Writing black box scripts (bbs)

This section introduces how to write down black box scripts (bbs) to create and execute pipelines.

3.1  The commands

In bbStudio , try typing in the Command area (in what follows, the commands entered by the user will be preceded by a prompt ) :
> help 

you get the list of the commands of the interpreter :
Available commands :

To get help on a particular command type help <command-name>, for example:
> help author

gives :
 usage : author <string>
  Adds the string <string> to the author information of the black box being defined

The help command has multiple usages. It is used to get help about almost anything in the interpreter! Type 'help help' to get help on the help command itself :
> help help
 usage : 
         (1) help 
         (2) help <command name> 
         (3) help packages [all]
         (4) help <package name> [all]
         (5) help <black box type> 
         (6) help <black box name>
  Effect :
         (1) Lists all available commands;
         (2) Prints help on a particular command; 
         (3) Lists the packages loaded and their black boxes.
             Add 'all' to list adaptors; 
         (4) Prints short help on the black boxes of a package.
             Add 'all' to include adaptors; 
         (5) Prints full help on a black box type; 
         (6) Prints information on the inputs, outputs and connectionns
	     of a black box instance.

3.2  Creating and executing black boxes

At start the interpreter does not know any black box. If you type 'help packages', which is the third form of the help command, you get :
> help packages

which means that the interpretor only knows one package (library of black boxes) called user and which contains a black box called workspace. The user package is an internal package of the interpreter, which stores user-defined black box types. At start, it already contains one box, called workspace. workspace is a special type of black box, called complex black box, whose purpose is to store other black boxes. Any black box you create in bbStudio is stored in workspace (this will be explained in details in sections and ).
If you type 'help workspace', you get :
> help workspace
 Complex Black Box <user::workspace>
  User's workspace
  By : bbtk
  Category(s) : complex box;
  * No inputs
  * No outputs
  * No boxes

In the text displayed, the user:: prepended to the name workspace means that the box workspace belongs to the user package. Then comes a description and three lines which tell that workspace does not have any input nor output nor boxes yet.
In order to let the interpreter know of some black boxes, you must load another package. The std package is the "standard" package, which contains basic useful black boxes.
To load it, type :
> include std

Then if you type :
> help packages

you get something like :

   ASCII                   : ascii codes sequence to string - string to ascii...
   Add                     : Adds its inputs
   ConcatStrings           : String concatenation
   Configuration           : Gets configuration informations
   Div                     : Divides its inputs
   ExecBbiCommand          : Executes bbi commands
   ExecSystemCommand       : Executes system (O.S.) commands
   GetVectorCharElement    : Gets the i-th element from the input vector (std...
   MagicBox                : Takes *any kind* of data and copies it to its ou...
   MakeFileName            : Makes a kosher file name
   Mul                     : Multiplies its inputs
   MultipleInputs          : This box has multiple Void inputs and one Void o...
   StringRelay             : Just copies the value of its input to its output...
   StringSelect            : Outputs the string set to the ith input Ini (In0...

Now the interpreter knows the package std and the black boxes it provides, such as the Add box, the ConcatStrings box, and so on. Remark that the content of std may vary from one version to another as new black boxes might be added to it. If you type :
> help Add

You'll get a text help, in the 'Message' part :
Black Box <std::Add>
  Adds its inputs
  By :
  Categories : atomic box;math;
  * Inputs : 
     'BoxExecute'     <bbtk::Void> [signal] : Any signal received by this input 
                                              executes the box
     'BoxProcessMode' <String>     []       : Sets the processing mode of the box 
                                              (Pipeline | Always | Reactive)
     'In1'            <Double>     []       : First number to add
     'In2'            <Double>     []       : Second number to add
  * Outputs : 
     'BoxChange'      <bbtk::VoidS> [signal] : Signals modifications of the box
     'Out'            <Double>     []       : Result

After loading the package it belongs to, you can create an instance of an Add box by the command new :
> new Add a

The 'a' at the end is the name of the instance, which will be used to reference it later. It is important to distinguish a box type and an instance of a box type. The Add box of the package std is actually a box type , like int is a data type in C langage. The new command allows to create an instance of a box type, exactly like int i; in a C code declares a variable of type int whose name is i. Of course, like in C Language, you can declare multiple boxes of the same type in bbi .
After the creation of the box a, type :
> help workspace

you get :
Complex Black Box <user::workspace>
 User's workspace
 By : bbtk
 Category(s) : complex box;
 * No inputs
 * No outputs
 * Boxes : 
    'a' <std::Add>

which means that bbi workspace now contains a black box named a, of type std::Add.
Help Add

and have a look to the 'Help' Part (see figure : )
Figure 13: The html Help
You can see a description (the one which was provided by the author of the box), the author(s) of the box (usually e-mail adress(es)) and the categories to which the box belongs. Finally comes the lists of inputs and outputs of the box. For each input or output, bbi provides its name , its type (between < and >, e.g. <Int>) and a description. Remark that the box Add is not a 'complex' black box but an 'atomic' box, hence its help does not include a pipeline graph.
You can see that Add boxes have two inputs, with name In1 and In2, and an output, with name Out.
You can set the input In1 of the Add box a to the value 1 by the command :
> set a.In1 1 

Similarly, setting the input In2 of a to the value 2 is done with :
> set a.In2 2

And you print the output Out of the box a with :
> print "result=$a.Out$"

In the string passed to the print command, each substring enclosed between a couple of $ is considered as the name of an output of a box. To process this special substrings, the interpretor :
  1. Processes the box if needed (see below)
  2. Converts the output of the box to a string if possible (see below)
  3. Substitutes the result in the string to print
  4. Postpones an implicit 'new line' character to the string
Box processing is needed if :
Note that all boxes have an input named 'BoxProcessMode'.
Another way to process the box a is to issue the command :
> exec a

however this command does not display anything (except if the box itself displays something in its processing). It just processes the box if needed. This command is used to execute boxes that do not have any output, such as boxes that write something to a file or, display a graphical interface, and so on.


3.3  Connecting black boxes

The Black Box Toolkit allows to create and execute processing chains, also called pipelines, by connecting black boxes. This section explains how to do it with examples. Read section to get more information on pipeline processing.
First start bbStudio and load the package std, typing :
> include std

in the 'Command' part.
Assume you want to compute 1+2+3. You can do it by chaining two Add boxes, as shown in figure .
Figure 14: A simple pipeline which adds 3 numbers
The bbi instructions to create and execute this pipeline are :
> new Add a
> new Add b
> connect a.Out b.In1
> set a.In1 1
> set a.In2 2
> set b.In2 3
> print $b.Out$

You will see the (very expected) result :

The first three commands build the pipeline, the next three set a and b black boxes inputs and the last one prints b black box output (the pipeline is executed before printing, because the interpretor 'knows' the box b, whose output is requested, is not up to date).
The command 'connect a.Out b.In1' "plugs" the output Out of the box a into the input In1 of the box b. Once the boxes are connected, the processing of the two boxes are chained : getting the output of b requires getting its inputs, hence getting the output of a which is connected to it. This pipeline mechanism can recurse into arbitrary long chains of boxes (see for details).
Lets' consider an other, more image oriented, example :
> include vtk
> include wx
> include itk
> include wxvtk

> new FileSelector fileDialog
> new ImageReader  reader 
> new Slider       slider
> new Viewer2D     viewer

> connect fileDialog.Out   reader.In 
> connect reader.Out       viewer.In
> connect slider.Out       viewer.Slice
> connect slider.BoxChange viewer.BoxExecute

> exec viewer

Some explainations : the include instructions load the necessary packages.
FileSelector will pop a File Selector, at run time, that will out the user chosen file name.
Slider will pop a Slider, at run time, that will out an integer, used later as a slice number.
ImageReader will read any itk readable file, whose name is passed as a std::string, and return a pointer on an itk image.
Viewer2D displays a plane, whose number is specified by an integer.

connect fileDialog.Out reader.In plugs the output of the File Selector (a std::string) to the input of the reader (a std::string, too).
connect reader.Out viewer.In plugs the output of the reader (an bbtk::any<bbitk::ImagePointer> which is a type defined by the itk package which can hold any itk image pointer) to the input of the Viewer (a vtkImageData *)
connect slider.Out viewer.Slice plugs the output of the slider (an int) to an other output (named Slide) of the viewer.
connect slider.BoxChange viewer.BoxExecute says the viewer that it must re process itself any time the slider is modified.

exec viewer processes the viewer.
This would correspond to the graph in figure
Figure 15: (Very) simple Graph of a (very) simple pipeline
Of course, to be able to connect two boxes, the output and the input must be compatibles. You can always connect an output to an input of the same type, but you can do more, thanks to particular (hidden) black boxes called adaptors.
An adaptor is a black box which has at least one input, called In, and at least one ouput called Out and whose role is to convert a data of the type of In into a data of the type of Out (other inputs or outputs may serve to parameter the adaptor or retreive other useful information).
Under bbStudio, if you type :
> load std
> help std all

you get :
 Package std v1.0.0 -
 Basic useful black boxes
 Black boxes : 
   BoolToString        [DA]  : Converts a Bool (bool) into a string
   CastBoolToChar      [DA]  : Static cast from Bool (bool) to Char (signed c...
   CastBoolToDouble    [DA]  : Static cast from Bool (bool) to Double (double...
   CastBoolToUChar     [DA]  : Static cast from Bool (bool) to UChar (unsigne...
   CastBoolToUInt      [DA]  : Static cast from Bool (bool) to UInt (unsigned...
   CastUIntToBool      [DA]  : Static cast from UInt (unsigned int) to Bool (...
   CastUIntToChar      [DA]  : Static cast from UInt (unsigned int) to Char (...
   CastUIntToDouble    [DA]  : Static cast from UInt (unsigned int) to Double...

[DA] stands for default adaptor.
Once you have loaded the package std, you can plug an output of type char into an input of type double. When the interpreter encounters the connect command, it looks for an adequate adaptor in the loaded packages. In our case, as the package std provides the CastUCharToDouble adaptor, the interpreter automatically creates an instance of this adaptor and place it between the output and the input you want to connect (however this adaptor is hidden to you, it is embedded into the created connection and does not appear as an existing black box). When the pipeline is processed the adaptor converts the output data into the required input type, in a totally transparent way. In our example, the CastUCharToDouble adaptor would simply cast the value of the char into a double, however arbitrarily complex type conversion may be done.
WARNING : these adaptors are C++ static cast, i.e., there is, right now, no 'intelligent' conversion (only truncation) e.g. think to CastDoubleToUChar!
Note that the set and print commands of interpreter work with adaptors from string to the type of the input to set or from the type of the output to print to string. Hence in order to set or print values the adequate adaptors must be available in the packages currently loaded.


3.4  Creating complex black boxes

Remember the pipeline of figure 14, which computed the sum of three doubles. You can consider it as a whole and define a new black box type, which will be a complex black box, having three inputs and one output, as shown in figure .
Figure 16: Creating the complex black box Add3
The bbi commands to define this complex black box are the following :
> load std
> define Add3
> new Add a
> new Add b
> connect a.Out b.In1
> author "myself"
> description "adds 3 doubles"
> input x a.In1 "first double to add"
> input y a.In2 "second double to add"
> input z b.In2 "third double to add"
> output result b.Out "output"
> endefine

Explainations :
As we will use Add boxes, we need to load the package std, which is done in first line.
The command define then starts the definition of the complex box type, which will be called Add3.
The next three lines define the pipeline, exactly in the same way than outside a complex box definition.
The commands author, description, input and output are commands specific to complex boxes definition :
author and description are used for the documentation of the new box. You can provide multiple author or description commands, the arguments of the commands will be concatenated to produce the final author and description strings.
input and output are used to define the inputs and outputs of the new complex box. Their syntax is the same : for each new input/output you need to say to which internal input/output it corresponds and to provide a help string documenting the input/output. In our example, we define that the box Add3 has three inputs : x, y and z. The input x corresponds to the input In1 of the internal box a. In the same way, the external input y corresponds to the internal input a.In2, and the external input In3 to b.In2. The only output of the new box is called result and corresponds to b.Out. The figure 16 illustrates the external to internal input/output correspondence.
Finally, the endefine command ends the definition of the new box type.
After this definition, if you ask for help on packages, you get :
> help packages

The user package now contains a new black box type, called Add3. If you ask for help on this type of box, you get :
> help Add3
Complex Black Box <user::Add3>
 adds 3 doubles
 By : myself
 * Inputs : 
    'x'      <double> : first double to add
    'y'      <double> : second double to add
    'z'      <double> : third double to add
 * Outputs : 
    'result' <double> : output
 * Boxes : 
    'a' <std::Add>
    'b' <std::Add>

and you can use it like any other box, for example type :
> new Add3 a
> set a.x 1
> set a.y 2
> set a.z 3
> print $a.result$

As a side note, we can say that, for consistency reasons, it would have been better to name In1, In2 and In3 the inputs of the black box Add3, since all the 'natural entry' of a box is named In, or Inx if there are more than one 'natural entry' .


3.5  Writing scripts files

Once you have defined a new type of complex box, you may like to reuse it. To do this, you can simply write the bbs commands defining the new box into a text file and afterwards include that file in bbi. Doing this, you start writing bbs scripts. The conventional (and mandatory) extension for such scripts is bbs (black box script). For consistency reasons, you are requested to prepend bb to the name.
For example, the Add3 complex box we previously worked on can be defined in the bbAdd3.bbs file :

File bbAdd3.bbs

# Defines the Add3 black box which adds 3 doubles 
load std

define Add3
  # I am the author 
  author "myself"
  description "adds 3 doubles"
  # Pipeline creation
  new Add a
  new Add b
  connect a.Out b.In1
  # Inputs definition
  input x a.In1 "first double to add
  input y a.In2 "second double to add
  input z b.In2 "third double to add"
  # Output definition
  output result b.Out "output"

End of file

Lines starting with a # character or a / / character are ignored, they are considered as comments by the interpreter. To use this file in bbStudio, click on the include button, and browse your filestore to find the file.
> include bbAdd3.bbs
> help Add3
Complex Black Box <user::Add3>
 adds 3 doubles
 By : myself
 * Inputs : 
    'x'      <double> : first double to add
    'y'      <double> : second double to add
    'z'      <double> : third double to add
 * Outputs : 
    'result' <double> : output
 * Boxes : 
    'a' <std::Add>
    'b' <std::Add>
and so on ...

If the file has the bbs extension, you can ommit it and just type :
> include Add3

3.6  Creating complex black boxes that use complex black boxes

Of course, you can include script files in other script files, like in the following example :

File bbAdd4.bbs

# Defines the Add4 black box which adds 4 doubles 
include Add3

define Add4
  author "myself"
  description "adds 4 doubles"
  new Add3 a
  new Add b
  connect a.Out b.In1
  input In1 a.In1 "first double to add
  input In2 a.In2 "second double to add
  input In3 a.In3 "third double to add"
  input In4 b.In2 "fourth double to add"
  output Out b.Out "output"

End of file

The inner boxes have they own entries (In1, In2, In3 for box a, In1, In2 for box b )
Only the inputs In1, In2, In3 of box a and the input In2 of box b is of interest for the end user, but he dosn't want to have to care neither about the inner boxes name, nor about the names of their Inputs.
The writer of the complex box has the ability to give these inputs a meaningfull name !
  input In3 a.In3 "third double to add"
  input In4 b.In2 "fourth double to add"

3.7  Naming Conventions


3.8  Creating command line applications

Now that you know how to create complex black boxes (with define/endefine), think back to the workspace object. Remember that it is also a complex black box. Actually, when you type interpreter commands outside a define/endefine block, you progressively define the workspace complex black box. You can think of it like if at start the interpreter was issuing a command 'define workspace' and then letting you define the interior of the box workspace.
Remember that the command inputs allows to define an input of a complex box. Now, if you use the command input outside a define/endefine block then it defines an input of the workspace box, that is an input of the main program. This input will then be connected to the parameters that the user passes to the command line.
For example, consider the script :

File add.bbs

load std
new Add a
input x a.In1 "first number to add"
input y a.In2 "second number to add"
print "x+y=$a.Out$"

End of file

The third and fourth lines define two inputs x and y. When you execute this script, you can pass these two arguments on the command line, like this :
> bbi add x=1 y=1

You can also invoke bbi the option -h, which gives help on the workspace box :
> bbi add -h
 User's workspace
 By : bbi (internal)
 * Inputs : 
    'x' <double> : first number to add
    'y' <double> : second number to add

To get a better help, use the description and author commands :

File add.bbs

description "Adds two numbers"
author ""
load std
new Add a
input x a.In1 "first number to add"
input y a.In2 "second number to add"
print "x+y=$a.Out$"

End of file

Now if you ask for help on the add script, you get :
> bbi add -h
 Adds two numbers
 By :
 * Inputs : 
    'x' <double> : first number to add
    'y' <double> : second number to add

Rather than getting the inputs of a script from the command line, you can ask bbi to prompt the user for the values, using the -t commutator :
> bbi add -t
x=[the program waits for user answer]2
y=[the program waits for user answer]5

You can also use the -g commutator. bbi then prompts the user in graphical mode, displaying a dialog box for each input, like in fig. .
Figure 17: Input dialog box
Note that for both -t and -g options, the input from the user is a string and bbi converts it to the right input type using an adaptor, hence the right adaptors must be loaded.


3.9  Using graphical interface boxes (widget boxes)

Basic graphical interface components are provided in the package wx, such as buttons, sliders, file open/save dialogs, etc.
As first example, type the following commands in bbi :
> load wx 
> new InputText t
> print $t.Out$\n

When you type enter after the last line, a window pops up in which you can entrer a text. When you close the window, the text you entered is printed by the print command.
Type help wx, you get something like :
 Package wx v1.0.0-
 Basic graphical interface elements (sliders, buttons ...) based on wxWidgets
 Black boxes : 
   ColourSelector        : Colour Selector dialog (bbfication of wxColourSele...
   ColourSelectorButton  : A button which displays a colour picker dialog whe...
   CommandButton         : Button which executes bbi commands
   DirectorySelector     : Pops up a directory selection dialog (wxDirDialog)
   FileSelector          : Pops up a file selection dialog for reading or sav...
   InputText             : A zone in which the user can enter a text (wxTextC...
   LayoutLine            : LayoutLine widget (wxBoxSizer)
   LayoutSplit           : Widget which splits a window in two fixed size par...
   LayoutTab             : LayoutTab widget (wxNotebook)
   OutputText            : Text zone to be inserted into a window (wxStaticTe...
   RadioButton           : RadioButton group widget 0-9 entries
   Slider                : Slider widget (wxSlider)

You can reproduce the same experiment as above using a Slider or a FileDialog rather than a InputText..
There is a special kind of widget, called 'Layout', designed to contain other widgets in order to build larger dialog boxes.
For example, the LayoutSplit widget is a container which "splits" a window into two parts, either horizontally or vertically, each part including another widget. The initial size of the two parts can be fixed by the input 'Proportion' and be adjusted by the user thanks to a "handle".
The example exampleLayoutSplit demonstrates its use. Run it : it displays a window with two sliders. Move the sliders and close the window. Now look at the source file to see how this is done :

File scripts/test/testSplit.bbs

load wx

new Slider s1
new Slider s2

new LayoutSplit s
connect  s1.Widget s.Widget1
connect  s2.Widget s.Widget2

exec s

End of file

First, the two sliders s1 and s2 are created. A LayoutSplit box s is also created. The connect commands then "includes" the sliders in the split widget. The input Widget is common to all widget boxes : every widget can be inserted into another widget. The outputs Widget1,Widget2 are specific of layout widgets (in bbi type help Slider : you will see the output Widget; type help LayoutSplit : you will see the inputs Widget1 and Widget2 and the output Widget). When you connect the Widget output of a box to the Widgeti input of a layout widget, you order to include the widget in the layout. Of course, the order of connection is important. In our case, the slider s1 is included first, then the slider s2 : s1 will be placed on top of s2 (the LayoutSplit box is implemented that way, but this is arbitrary choice).
Right now, there are only three layout widgets in the wx package :

3.10  Deeper in the boxes

3.10.1  Default and mandatory inputs and outputs

4  Using third party Package

4.1  Plugging in a Package

bbStudio makes it easy for you : in the menu Tools just click on the option Plug Package. You will be asked to 'Select package directory'. Browse untill you find the install or the build directory, depending whether you installed the package or not.
bbStudio will update the configuration file, generate the 'Package documentation', and update the 'Boxes Lists'.
You will be able to use the new package just as you did for any other bbtk canonical Package.

4.2  Hard incorporating of a Package

If the Package you want to use is supplied in a non standard way (e.g. : you where given one ore more dynamic libraries (.dll or .so), and/or one or more directories containing bbtk scripts (.bbs) you can edit your bbtk configuration and add the appropriate paths, see .

4.3  Updating the documentation

You may add your own boxes (simple boxes, if you are aware enough in C++ language, or complex boxes if you are aware enough in bbtk scripting).
To update the html help of this package, use the option Regenerate package doc in the menu Tools of bbStudio. You'll be prompted for the Package name. Avoid using the -a option (Regenerate all), since it's time consumming.
To update html boxes lists with the new boxes, use the option Regenerate Boxes Lists in the menu Tools of bbStudio.

4.4  Using the package

The only thing you have to do is to include or load the package, within a script, or from the Command part, and enjoy the black boxes it contains.

5  Using black boxes in C++ programs

A very useful feature is that you may use any widget black box within a C++ program without worrying about writing a wxWidgets main application.
Let's look a the following bbs script :
# Load the packages
load std
load wx

# Create the Objects
new Slider     slider
new OutputText text
new LayoutLine layout

# Graphical pipeline
connect slider.Widget    layout.Widget1
connect text.Widget      layout.Widget2

# Execution pipeline
connect slider.BoxChange text.BoxExecute
connect slider.Out       text.In

# Go!
exec layout

User wants to create a slider and an output text, within a LayoutLine, and display the slider value in the output text. Think about the (little!) nightmare to code the same, in 'raw C++', using wxWidgets.
The following C++ code does the same :
#include <bbtkFactory.h>
#include <bbwxSlider.h>
#include <bbwxOutputText.h>
#include <bbwxLayoutLine.h>

int main(int argv, char* argc[])
      // we need to intanciate a bbtk::Factory to be aware of the adaptors
      bbtk::Factory::Pointer factory = bbtk::Factory::New();
      // Load the packages
      // ----------------  
      // Create the Objects
      // ------------------      
      bbwx::Slider::Pointer     slider   = bbwx::Slider::New("slider");
      bbwx::OutputText::Pointer text     = bbwx::OutputText::New("text");
      bbwx::LayoutLine::Pointer layout   = bbwx::LayoutLine::New("layout");
      // Graphical pipeline
      bbtk::Connection::Pointer c1       = bbtk::Connection::New(slider,"Widget",
      bbtk::Connection::Pointer c2       = bbtk::Connection::New(text,"Widget",
      // Execution pipeline
      // ------------------
      // We have to pass the 'factory', in order to call automatically an adaptor,
      // if necessary.
      bbtk::Connection::Pointer s2t      = bbtk::Connection::New(slider,"Out",
      bbtk::Connection::Pointer c3       = bbtk::Connection::New(slider,"BoxChange",
      // Go!
      // ---     

  catch (bbtk::Exception e)

In this code, we use the headers of the \texttt{bbwx} \CPP library, 
which define the black boxes of the \texttt{wx} package. 

to be continued ...

6  bbs language reference

6.1  Pipeline creation and execution related commands

Table 1: bbs pipeline creation and execution related commands.
Command Parameters Effect
new <box-type> <box-name>Creates a box of type box-type and name box-name.
newgui <box-name> <gui-box-name> Automatically creates a graphical user interface with name gui-box-name for the black box box-name and connects it to the box inputs
delete <box-name> Destroys the box named box-name
connect <box1.output> <box2.input> Connects the output output of the box named box1 to the input input of the box named box2
set <box.input> <value> Sets the input input of the box named box to the value value. An adaptor must exist in the packages loaded which converts a std::string to the type of the input input.
exec <box-name> Executes the box named box-name. If needed the boxes connected to its inputs are also processed recursively (pipeline processing).
freeze Allows to block execution commands while keeping definition commands active (this one is not for end user)
unfreeze Turns back to 'normal' mode (this one is not for end user).

6.2  Package related commands

Table 2: bbs package related commands.
Command Parameters Effect
include <package-name> Loads the package package-name and includes all its complex box definition scripts.
load <package-name> Loads the atomic black boxes of package package-name. Loads the dynamic library but not the complex boxes defined in the scripts shipped with the package. Use it only if you know that you won't work with its complex black boxes
unload <package-name>Unloads the package package-name. The package must have been previously loaded. No box of a type defined in this package must still exist.
reset - Deletes all boxes and unloads all packages so that the interpreter gets back to its initial state
package <package-name> All complex black boxes definitions until the next endpackage will be stored into the package package-name
endpackage - Closes a package command

6.3  Interpreter related commands

Table 3: bbs intepreter related commands.
Command Parameters Effect
help - Prints help on available commands
<command-name> Prints help on the command command-name
packages Prints help on available packages and their box types (without description)
<package-name> Prints help on the package package-name and its boxes (with brief description). The package must have been previously loaded
<box-type> Prints help (with full description) on the type of box box-type. The box type must belong to a package which has been previously loaded
message - Prints information on available kinds of messages and their current level
<kind> <level> Sets the level of verbosity of the interpreter for the kind of messages kind to level.
include <file-name> Includes and executes the content of the file named file-name exactly like if you were typing its content at the place were the include command is.
print <string> Prints the string after substituting each token of the form $box.output$ by the adaptation to string of the value of the output output of the box named box. An adaptor must exist in the packages loaded which converts the type of the output output to a std::string.
graph ... Generates the html doc including the pipeline graph for a given complex box
index ... Generates the html index of currently loaded boxes types
config - Displays the configuration parameters
debug <debug-directive> [expr - -C - -D] Prints debug info on living bbtk objects containing the string expr (default expr="). -C checks the factory integrity. -D turns on objects debug info after main ends
quit - Exits the interpreter

6.4  Complex black box definition related commands

Table 4: bbs complex black box definition related commands.
Command Parameters Effect
define <box-type> [<package-name>] Starts the definition of a complex black box of type box-type. If <package-name> is provided then includes the box in the given package (otherwise it is defined in the current package, i.e. user if outside a package/endpackage block).
endefine - Ends the definition of a complex black box type
author <string> Concatenate the string to the author string of the current complex black box.
description <string> Concatenate the string to the description of the current complex black box.
category <string> Specifies the categories of the current complex black box. The categories must be separated by semicolons, e.g. "widget;image"
kind <box kind> Specifies the kind of the current complex black box ( ADAPTOR, DEFAULT_ADAPTOR, WIDGET_ADAPTOR, DEFAULT_WIDGET_ADAPTOR )
input <name> <box.input> <help> Defines a new input for the current complex black box, named name. It is defined as corresponding to the input input of the box box.
<help> is the help string for the new input. The box box must already have been created in the complex box and of course have an input named input.
output <name> <box.output> <help> Defines a new output for the current complex black box, named name. It is defined as corresponding to the output output of the box box. <help> is the help string for the new output. The box box must already have been created in the complex box and of course have an output named output.
Note : if outside a define/endefine block then the current complex black box is 'user::workspace', that is the main program equivalent (this is how applications are documented). This remark holds for all complex black box related commands.

7  Install and run time issues

7.1  bbtk configuration file

At start, bbtk applications (bbStudio , bbi ) try to open an xml configuration file named bbtk_config.xml. The search order is
  1. The current directory
  2. The subdir .bbtk of the user's home directory.
  3. If none of these two paths contains the file then it creates a new one in the .bbtk directory.
Information on bbtk configuration is obtained in bbStudio by clicking on the Config button of the Command part toolbar.
If you did not installed other packages than the ones provided by bbtk , you get something like :
 bbtk_config.xml    : [/home/guigues/.bbtk/bbtk_config.xml]
 Documentation Path : [/usr/local/bin/../share/bbtk/doc]
 Data Path          : [/usr/local/bin/../share/bbtk/data]
 Temp Directory     : []
 File Separator     : [/]
 BBS Paths   
 --- [.]
 --- [/usr/local/bin/../share/bbtk/bbs]
 PACKAGE Paths : 
 --- [.]
 --- [/usr/local/bin/../lib]

The first line let you know which configuration file is currently used.
You can open this file using bbStudio menu Files > Open bbtk Config file.
You will get something like :
<?xml version=\"1.0\" encoding=\"iso-8859-1\"?>
  <bbs_path>     </bbs_path>
  <package_path> </package_path> 

The xml tags bbs_path and package_path allow to set additionnal directories in which to search for bbs files and packages dynamic libraries.
For example, if you add the line :
  <bbs_path> /home/guigues/bbs </bbs_path>

Then the interpreter will search for bbs in the folder /home/guigues/bbs, which allows a command like 'include bbMyBox.bbs' to work if the folder /home/guigues/bbs contains the file bbMyBox.bbs.
The same, the xml tag <package_path> let you set additional path in which to find a package dynamic library, hence allowing to load additionnal packages with the 'load' command.
All bbs and package paths are summmarized in the information output when pressing 'Config' in bbStudio . You can see that two bbs paths are always set : Also, two package paths are always set :
Additional paths set in your bbtk_config.xml are added after those standard paths. Note that the order displayed is the one in which the folders are searched when include or load commands are issued.

7.2  Misc


1Yes, we know : all the arrows (graphical interface pipeline arrows and data processing arrows) are blue; using different colors is planned for next release...

File translated from TEX by TTH, version 3.81.
On 12 Nov 2008, 11:39.