=head1 Programming PerlTQt B This document describes a set of Perl bindings for the TQt toolkit. Contact the author at =head1 Introduction PerlTQt-3 is Ashley Winters' full featured object oriented interface to L's C++ TQt toolkit v3.0. It is based on the L library, a language independent low-level wrapper generated from TQt headers by Richard Dale's L thanks to David Faure's module. This document describes the principles of PerlTQt programming. It assumes you have some basic Perl Object Oriented programming knowledge. Some C++ knowledge is recommended but not required. It would mostly help you to find your way through L which is our ultimate and only reference. If TQt is installed on your system, then you most probably also have its documentation. Try the C<$TQTDIR/bin/assistant> program. =head1 Installation =head2 Requirements To compile and use PerlTQt, you'll need : =over 4 =item * a POSIX system =item * GNU tools : automake(>=1.5), autoconf (>=2.13), aclocal... =item * L= v5.6.0|"http://www.perl.org"> =item * L= v3.0|"http://www.trolltech.com/developer/download/qt-x11.html"> =item * L The SMOKE library (Scripting Meta Object Kompiler) is part of L's B module. You may want to check if a precompiled version of this module exists for your system. PerlTQt is packaged with its own copy, so you don't need to check it out. =back Perl and TQt's installation is out of the scope of this document. Please refer to those projects' documentation. =head2 Compilation PerlTQt uses GNU's Autoconf framework. However, the standard ./configure script is preferably driven by the Makefile.PL wrapper. All options are forwarded to ./configure : perl Makefile.PL If SMOKE is missing, C will generate its sources. Then : make make install This will install PerlTQt, Puic and Smoke (if needed), as well as the pqtsh and pqtapi utilities. The preferred install location for SMOKE and Puic is in the KDE3 file system. If you don't have KDE3 installed, specify a location with C's C<--prefix> option. e.g: perl Makefile.PL --prefix=/usr =head2 Troubleshooting and Configure Options If Smoke's linking fails or your TQt library was built with very specific options, run Makefile.PL again with: perl Makefile.PL --with-threshold=0 When building smoke, configure will check for OpenGL and try to compile support for it if it is properly installed and supported by TQt. You may disable this checking with: --disable-GL Also, default behaviour is to prefer the Mesa GL library over a proprietary implementation. If your system features a proprietary OpenGL library, and you'd like to use it, specify: --without-Mesa =head2 How to install PerlTQt with user rights To install PerlTQt without super-user rights, simply follow this procedure: =over 4 =item * Perform a normal configuration, specifying as prefix a directory where you have write permissions : perl Makefile.PL --prefix=~ The above would install the Smoke library in ~/lib and the puic binary in ~/bin =item * Reconfigure the Perl module so that it doesn't target the standard perl hierarchy: cd PerlTQt perl Makefile.PL PREFIX=~ cd .. Beware : this is not the same Makefile.PL as above, but the one located in the ./PerlTQt subdirectory =item * Compile and Install make && make install In order to use such an installation, you must tell to Perl where to find this extern hierarchy. This can be done either on the command line: perl -Mlib="~/local/lib/perl/5.x.x" program.pl or at the top of your program: use lib qw( ~/local/lib/perl/5.x.x ); "5.x.x" should be changed to whatever Perl version your system is running. =back =head1 Anatomy of PerlTQt A typical TQt program using GUI components is based on an event loop. This basically means that such a program is no more envisioned as a straight flow where you would need to handle yourself every single events (such as a mouse click or a key press). Instead, you just create an B object, create the GUI components it uses, define what objects methods need to be called when an event occurs, and then start the main event loop. That's all! TQt will handle all events and dispatch them to the correct subroutine. Lets see how this process is implemented in a minimal PerlTQt program. =head2 Hello World 1: use TQt; 2: my $a = TQt::Application(\@ARGV); 3: my $hello = TQt::PushButton("Hello World!", undef); 4: $hello->resize(160, 25); 5: $a->setMainWidget($hello); 6: $hello->show; 7: exit $a->exec; =for html
This program first loads the TQt interface [line 1] and creates the application object, passing it a reference to the command line arguments array C<@ARGV> [l.2]. This application object is unique, and may later be accessed from anywhere through the B pointer. At line 3, we create a PushButton, which has no parent (i.e : it won't be contained nor owned by another widget). Therefore, we pass to the constructor an B value for the parent argument, which is PerlTQt's way of passing a Null pointer. After some layouting at [l.4], we tell the application object that our main widget is this PushButton [l.5]... that way, it will know that closing the window associated with this widget means : I. Now the last steps are to make this widget visible (as opposed to hidden, which is the default) by calling the B method on it [l.6] and to start the application loop [l.7]. B =over 4 =item 1 All TQt classes are accessed through the prefix B, which replaces the initial B of TQt classes. When browsing the L, you simply need to change the name of classes so that B reads B. =item 2 An object is created by calling the B of the class. It has the same name as the class itself. You don't need to say C or Cnew()> as most Perl programmers would have expected. Instead, you just say : my $object = TQt::(arg_1, ..., arg_n); If you don't need to pass any argument to the constructor, simply say : my $object = TQt::; =item 3 Whenever you need to pass a Null pointer as an argument, use Perl's B keyword. Do not pass zero. Beware: this is by far the most common error in PerlTQt programs. Pointers are arguments preceded by an B<*> character in TQt's documentation (e.g: "C"). =back =head2 Inheritance and Objects Before we can discuss how Perl subroutines can be called back from TQt, we need to introduce PerlTQt's inheritance mechanism. PerlTQt was designed to couple as tightly as possible TQt's simplicity and Perl's power and flexibility. In order to achieve that goal, the classical Object Oriented Perl paradigm had to be extended, much in the same way than TQt itself had to extend C++'s paradigm with B. =head3 A Custom Widget Lets rewrite the "Hello World!" program, this time using a custom version of PushButton: 1: use strict; 2: 3: package Button; 4: use TQt; 5: use TQt::isa qw(TQt::PushButton); 6: 7: sub NEW 8: { 9: shift->SUPER::NEW(@_[0..2]); 10: resize(130, 40); 11: } 12: 13: 1; 14: 15: package main; 16: 17: use TQt; 18: use Button; 19: 20: my $a = TQt::Application(\@ARGV); 21: my $w = Button("Hello World!", undef); 22: $a->setMainWidget($w); 23: $w->show; 24: exit $a->exec; Here, we want to create our own version of the PushButton widget. Therefore, we create a new package for it [l.3] and import TQt [l.4]. We now want to declare our widget as subclassing PushButton. This is done through the use of the C pragma [l.5], which accepts a list of one or more parent TQt classes. It is now time to create a B for our new widget. This is done by creating a subroutine called B I<(note the capitalized form, which differentate it from the usual "new" constructor. PerlTQt's NEW constructor is called >BI< as can be seen on line 21)>. Since we want our widget to call its parent's constructor first, we call the B (here: TQt::PushButton) on line 9, passing it all arguments we received. At this time, a class instance has been created and stored into a special object holder named B (not C<$this> but really just C). Each time you invoke a method from within your package, you may now indifferently say C or Cmethod()>; =head3 Using Attributes When building a new composite widget, you may just create its different parts inside B variables, since widgets are only deleted by their parents and not necessarily when their container goes out of scope. In other words, PerlTQt performs clever reference counting to prevent indesirable deletion of objects. Now, you'll often want to keep an access to those parts from anywhere inside your package. For this purpose, you may use the B object's blessed hash, as is usual in Perl, but that isn't really convenient and you don't have any compile time checking... Here come B. Attributes are data holders where you can store any kind of properties for your object. Declaring new attributes is done through the C pragma, as is demonstrated in the following package implementation : 1: use strict; 2: 3: package Button; 4: use TQt; 5: use TQt::isa qw(TQt::PushButton); 6: use TQt::attributes qw( 7: itsTime 8: pData 9: ); 10: 11: sub NEW 12: { 13: shift->SUPER::NEW(@_[0..2]); 14: itsTime = TQt::Time; 15: itsTime->start; 16: pData = " Foo "; 17: } 18: 19: sub resizeEvent 20: { 21: setText( "w: ". width() ." h: ". height() . 22: "\nt: ". itsTime->elapsed . pData ); 23: } 24: 25: 1; =for html
An attribute itsTime is declared at line 7, and loaded with a C object at line 14. Since we reimplement the virtual function "resizeEvent" [l.19]. each time the main widget is resized, this function will be triggered and our Button's text updated with values coming from the object [l.21] and from the attributes we defined [l.22]. B =over 4 =item * In order to inherit a TQt class, a package must contain a C pragma. e.g: use TQt::isa "TQt::widget"; =item * The object constructor is named B and is implicitly called. Thus you should not say : my $o = MyButton->NEW("Hello"); But say : my $o = MyButton("Hello"); =item * Within a package, the current instance can be accessed through the B variable. When a member function is called, arguments are loaded as usual in the B<@_> array, but B the object pointer itself. Hence, you shouldn't say : sub myMember { my $self = shift; my $arg = shift; $arg->doThat($self); $self->doIt; } But : sub myMember { my $arg = shift; $arg->doThat(this); doIt; } Furthermore, if you want to call a base class method from a derived class, you'd use the specal attribute SUPER : sub example { print "Now calling the base class\n"; SUPER->example(@_) } Note that the : this->SUPER::Example(@_); construct is also available, but will pass the object as first argument. =item * Whenever you need to store a contained object in your package, you may define it as an B : use TQt::attributes qw( firstAttribute ... lastAttribute); and then use it as a convenient accessor : firstAttribute = myContainedWidget( this ); firstAttribute->resize( 100, 100 ); =item * To reimplement a B, simply create a B with the same name in your object. Existing virtual functions are marked as such in TQt's documentation (they are prefixed with the "virtual" keyword). You can inspect what virtual function names are being called by TQt at runtime by putting a C statement at the top of your program. =back =head2 Signals and Slots We'll now learn how TQt objects can communicate with each other, allowing an event occuring, for instance, in a given widget to trigger the execution of one or several subroutines anywhere inside your program. Most other toolkits use callbacks for that purpose, but TQt has a much more powerful and flexible mechanism called B. Signals and slots are used for communication between objects. This can be thought off as something similar to the wiring between several Hi-fI components : an amplificator, for instance, has a set of output signals, wich are emitted wether a listening device is connected to them or not. Also, a tape recorder deck can start to record when it receives a signal wired to it's input slot, and it doesn't need to know that this signal is also received by a CD recorder device, or listened through headphones. A TQt component behaves just like that. It has several output B and several input B - and each signal can be connected to an unlimited number of listening slots of the same type, wether they are inside or outside the component. The general syntax of this connection process is either : TQt::Object::connect( sender, TQT_SIGNAL 'mysignal(arg_type)', receiver, TQT_SLOT 'myslot(arg_type)'); or myObject->connect( sender, TQT_SIGNAL 'mysignal(arg_type)', TQT_SLOT 'myslot(arg_type)'); This mechanism can be extended at will by the declaration of custom Signals and Slots, through the C and C pragma (see also the other syntax, later on). Each declared slot will call the corresponding subroutine in your object, each declared signal can be raised through the B keyword. B 1: use strict; 2: 3: package Button; 4: use TQt; 5: use TQt::isa qw(TQt::PushButton); 6: use TQt::attributes qw(itsTime); 7: use TQt::slots 8: wasClicked => [], 9: change => ['int', 'int']; 10: use TQt::signals 11: changeIt => ['int', 'int']; 12: 13: sub NEW 14: { 15: shift->SUPER::NEW(@_[0..2]); 16: itsTime = TQt::Time; 17: itsTime->start; 18: this->connect(this, TQT_SIGNAL 'clicked()', TQT_SLOT 'wasClicked()'); 19: this->connect(this, TQT_SIGNAL 'changeIt(int,int)', TQT_SLOT 'change(int,int)'); 20: } 21: 22: sub wasClicked 23: { 24: my $w = width(); 25: my $h = height(); 26: setText( "w: $w h: $h\nt: ". itsTime->elapsed ); 27: emit changeIt($w, $h); 28: } 29: 30: sub change 31: { 32: my ($w, $h) = @_; 33: print STDERR "w: $w h: $h \n"; 34: } 35: 36: 1; In this package, we define two extra slots and one extra signal. We know from the TQt Documentation that a clicked PushButton emits a C signal, so we connect it to our new slot at line 18. We also connect our signal C to our own C slot- which is quite stupid, but as an example. Now, whenever our Button is clicked, the C signal is raised and triggers the C slot. C then proceeds to emit the C signal [l.27], hence triggering the C slot with two arguments. Finally, since PerlTQt-3.008, an alternative syntax can be used to declare Signals and Slots: sub a_slot : TQT_SLOT(int, TQString) { $int = shift; $string = shift; # do something } and sub a_signal : TQT_SIGNAL(TQString); This syntax is perfectly compatible with the traditional C and C declarations. Eventually, it can prove good programming practice to mix both syntaxes, by first declaring Signals/Slots with C, then repeat this declaration in the actual implementation with the second syntax. Declarations will be checked for consistency at compile time, and any mismatch in arguments would trigger a warning. =head1 RAD prototyping with TQt Designer and Puic =head2 Introduction =over 4 =item * Note: As of PerlTQt-3.008, a separate PerlTQt plugin for TQt Designer is available, bringing full integration, syntax highlighting, code completion and allowing to run/debug your PerlTQt project entirely from the Designer GUI. Nevertheless, the below is still accurate with regard to puic command line interaction and with regard to using TQt Designer I the specific plugin. =back As efficient and intuitive as TQt can be, building a complete GUI from scratch is often a tedious task. Hopefully, TQt comes with a very sophisticated GUI Builder named TQt Designer, which is close to a complete integrated development environment. It features Project management, drag'n drop GUI building, a complete object browser, graphical interconnection of signals and slots, and much much more. TQt Designer's output is XML which can be parsed by several command line tools, among whose is B (the PerlTQt User Interface Compiler). Assuming you have already built an interface file with the Designer, translating it to a PerlTQt program is simply a matter of issuing one command : puic -x -o program.pl program.ui This will generate the package defined in your ui file and a basic main package for testing purposes. You may prefer : puic -o package.pm program.ui This will only generate the package, which can then be used by a separate program. =head2 Embedding Images If you need to B, it can be done in two ways : =over 4 =item * Inline embedding For this, you need to check the "Edit->Form Settings->Pixmaps->Save inline" checkbox inside TQt Designer. Then : puic -x -o F F =item * Image Collection This option is more complex but also far more powerful and clean. puic -o F -embed F F ... F Then add a C statement to your program's main package. If you've created a project file in TQt Designer, and added all images you want to group (through "Project->Image Collection"), you'll find all those images inside the directory where your project file (*.pro) is stored, under /images. You can then generate the corresponding image collection by issuing : puic -o F -embed F ../images/* You can use as many image collections as you want in a program. Simply add a B statement for each collection. =back =head2 Working With B<.ui> Files It will often happen that you need to regenerate your user interface -either because you changed your initial design, or you want to extend it. Thus writing your program's code straight in the auto-generated Perl file is quite a bad idea. You'd run constantly the risk of overwriting your handcrafted code, or end up doing lot of copy-paste. Instead, you may : =over 4 =item * Write slots implementation in the Designer In TQt Designer, select the I tab of the B. There you can see a tree-like representation of your classes. Now if you double-click on the I entry, you are prompted with a dialog where you can create a new custom slot for your module. Once this is done, the new slot appear inside the B tree and clicking on it will bring you to a BYour ClassE.ui.h> file where you can write the actual implementation of your slot. Keeping all the defaults, it should look like this : void Form1::newSlot() { } The slot declaration is actually C++ code, but simply ignore it and write your Perl code straight between the two braces, paying special attention to indent it at least by one space. void Form1::newSlot() { print STDERR "Hello world from Form1::newSlot(); if(this->foo()) { # do something } } All Perl code written this way will be saved to the ui.h file, and B will take care of placing it back in the final program. Here, after running B on the Form1.ui file, you'd have: sub newSlot { print STDERR "Hello world from Form1::newSlot(); if(this->foo()) { # do something } } =item * Subclassing your GUI By using B's I<-subimpl> option, you may generate a derived module inheriting your original user interface. You'd typically generate the derived module once, and write any handcrafted code in this child. Then, whenever you need to modify your GUI module, simply regenerate the parent module, and your child will inherit those changes. To generate the base module : puic -o Form1.pm form1.ui (do this as often as needed, never edit by hand) To generate the child : puic -o Form2.pm -subimpl Form2 form1.ui or puic -o program.pl -x -subimpl Form2 form1.ui (do this once and work on the resulting file) =back =head1 More development tools PerlTQt comes bundled with two simple programs that can help you to find your way through the TQt API: =head2 pqtapi pqtapi is a commandline driven introspection tool. usage: pqtapi [-r ] [] options: -r : find all functions matching regular expression/keyword -i : together with -r, performs a case insensitive search -v : print PerlTQt and TQt versions -h : print this help message e.g: $>pqtapi -ir 'setpoint.* int' void TQCanvasLine::setPoints(int, int, int, int) void TQPointArray::setPoint(uint, int, int) =head2 pqtsh B is a graphical shell that can be used to test the API interactively. It is fairly self explanatory and includes an interactive example (CExample>) =for html
=head1 Known Limitations Templated classes aren't available yet (classes derived from templated classes are). =head1 Credits PerlTQt-3 is (c) 2002 Ashley Winters (and (c) 2003 Germain Garand) Kalyptus and the Smoke generation engine are (c) David Faure and Richard Dale Puic is (c) TrollTech AS., Phil Thompson and Germain Garand, The mentioned software is released under the GNU Public Licence v.2 or later. =head1 Appendix 1 : C++ conventions and their Perl counterpart Whenever you want to use a class/method described in TQt's L (see also the 'assistant' program bundled with TQt) from PerlTQt, you need to follow some simple translation rules. =over 4 =item Classnames =over 4 =item * All classnames are changed from a B prefix in TQt to a B prefix in Perl. e.g: TQComboBox is named TQt::ComboBox within PerlTQt. =back =item Functions =over 4 =item * Functions referenced as B are accessed directly, and not through an object. Thus the static function Foo in class TQBar would be accessed from PerlTQt as TQt::Bar::Foo( arg-1,...,arg-n); The only notable exceptions are : tqApp() will map to TQt::app() qVersion() will map to TQt::version() # not really needed anymore: we have qVersion(). See Global Functions below. =item * Functions referenced as B or B are accessed through an object with the B<-E> operator. e.g: $widget->show; There are no fundamental differences between methods and signals, however PerlTQt provides the B keyword as a convenient mnemonic, so that it is clear you are emitting a signal : emit $button->clicked; =back =item Arguments =over 4 =item * By value When an argument isn't preceded by the B<&> or B<*> character, it is passed by value. For all basic types such as int, char, float and double, PerlTQt will automatically convert litteral and scalar values to the corresponding C++ type. Thus for a constructor prototype written as follow in the documentation : TQSize ( int w, int h ) You'd say : TQt::Size(8, 12); =item * By reference When an argument is preceded by the B<&> character, it means a reference to an object or to a type is expected. You may either provide a variable name or a temporary object : $keyseq = TQt::keySequence( &TQt::CTRL + &TQt::F3 ); $widget->setAccel( $keyseq ); or $widget->setAccel(TQt::keySequence( &TQt::CTRL + &TQt::F3 ); If the argument isn't qualified as B (constant), it means the passed object may be altered during the process - you must then provide a variable. =item * By pointer When an argument is preceded by the B<*> character, it means a pointer to an object or to a type is expected. You may provide a variable name or the Perl B keyword for a Null pointer. Similarly, if the argument isn't B, the passed object may be altered by the method call. =back =item Enumerations Enumerations are sort of named aliases for numeric values that would be hard to remember otherwise. A C++ example would be : enum Strange { Apple, Orange, Lemon } where C is the generic enumeration name, and C, C, C its possible values, which are only aliases for numbers (here 0, 1 and 2). Access to enumerations values in Perl TQt is very similar to a static function call. In fact, it B a static function call. Therefore, since you probably want to avoid some readability problems, we recommend the use of the alternate function call syntax : C<&function>. Lets now go back to our C example. If its definition was encountered in the class C, you'd write from PerlTQt : $apple_plus_orange = &TQt::Fruit::Apple + &TQt::Fruit::Orange; =item Operators Within PerlTQt, B works transparently. If a given operator is overloaded in a TQt class (which means using it triggers a custom method) it will behave identically in PerlTQt. Beware though that due to limitations of the Smoke binding library, not all overloaded operators are available in PerlTQt. You can check the availability of a given operator by using the pqtapi program. Also, due to outstanding differences between C++'s and Perl's object paradigm, the copy constructor operator (a.k.a '=') has been disabled. e.g-1: '+=' overload $p1 = TQt::Point(10, 10) $p2 = TQt::Point(30,40) $p2 += $p1; # $p2 becomes (40,50) e.g-2: '<<' overload $f = TQt::File("example"); $f->open( IO_WriteOnly ); # see 'Constants' below $s = TQt::TextStream( $f ); $s << "What can I do with " << 12 << " apples?"; =item Constants TQt doesn't use many constants, but there is at least one place where they are used : for setting Input/Output flags on files. In order to avoid the namespace pollution induced by global constants, PerlTQt group them in the B module. For instance, requesting the importation of all IO constants into the current namespace would be done with: use TQt::constants; You may also import specific symbols: use TQt::constants qw( IO_ReadOnly IO_WriteOnly ); =item Global Functions TQt has also some utilitarian functions such as bitBlt, qCompress, etc. Those were global scope functions and have been grouped in a common namespace: C. Hence, you shall access this namespace either with a fully qualified call: TQt::GlobalSpace::tqUncompress( $buffer ) Or directly, after importation in the current namespace: use TQt::GlobalSpace; tqUncompress( $buffer ) Of course, you may selectively import a few functions: use TQt::GlobalSpace qw( tqUncompress bitBlt ) B GlobalSpace has also operators, such has the one performing an addition on two TQt::Point(). Those operators are called automatically. e.g: $p1 = TQt::Point(10, 10) + TQt::Point(20, 20) =back =head1 Appendix 2 : Internationalization PerlTQt handles internationalization by always converting B back to B in Perl. Conversions from Perl strings to TQStrings are made according to context : =over 4 =item * If the Perl string is already utf8-encoded then the string will be converted straight to TQString. This is the most convenient and seemless way of internationalizing your application. Typically, one would just enable the use of utf8 in source code with the C pragma and write its application with an utf8 aware editor. =item * If the string isn't tagged as utf8, and the B pragma is not set then the string will be converted to TQString's utf8 from B. =item * If the string isn't tagged as utf8 and the B pragma is set then the string will be converted to TQString's utf8 according to the currently set B. =back Once a string contains utf8, you can convert it back to any locale by setting up B : $tr1=TQt::TextCodec::codecForLocale(); # this one will use current locale $tr2=TQt::TextCodec::codecForName("KOI8-R"); # that one forces a specific locale (Russian) print $tr1->fromUnicode(TQt::DateTime::currentDateTime()->toString)."\n\n"; print $tr2->fromUnicode($my_utf8_string); Or, with Perl >= 5.8.0, you may use Perl's B modules (see C). =head3 disabling utf-8 Developers who don't want to use UTF-8 or want to temporarily disable UTF-8 marshalling for handling legacy programs may use the B pragma (and the corresponding B). Within the scope of this pragma, TQStrings are marshalled back to ISO-Latin1 (default) or to your locale (if B has been set). Frivole use of this pragma is strongly discouraged as it ruins worldwide standardization efforts. =head1 Appendix 3 : Debugging Channels The B module offers various debugging channels/features. use TQt::debug; use TQt::debug qw|calls autoload verbose|; With the simple C statement, the B and B channels are activated. If you specify a list of channels within the use statement, then only the specified channels will be enabled. B =over 4 =item * ambiguous Check if method and function calls are ambiguous, and tell which of the alternatives was finally elected. =item * verbose Enable more verbose debugging. Together with B, tell you the nearest matches in case a method or function call fails. e.g: use TQt; use TQt::debug; $a= TQt::Application(\@ARGV); $a->libraryPath("foo"); --- No method to call for : TQApplication::libraryPath('foo') Closer candidates are : static void TQApplication::addLibraryPath(const TQString&) static TQStringList TQApplication::libraryPaths() static void TQApplication::removeLibraryPath(const TQString&) static void TQApplication::setLibraryPaths(const TQStringList&) =item * calls For every call, tell what corresponding TQt method is called (detailing the arguments if B is on). =item * autoload Track the intermediate code between a method invocation in Perl and its resolution to either a TQt or Perl call. =item * gc Give informations about garbage collection whenever a TQt object is deleted and/or a Perl object is destroyed =item * virtual Report whenever a virtual function tries to access its Perl reimplementation (wether it exists or not). =item * all Enable all channels =back =head1 Appendix 4 : Marshallers A marshaller is a piece of "glue code" translating a given datatype to another. Within PerlTQt, most TQt objects keep their object nature, so that one may invoke methods on them. However, some classes and datatypes map so naturally to some Perl types that keeping their object nature would would feel unnatural and clumsy. For instance, instead of returning a TQt::StringList object, which would require an iterator to retrieve its content, PerlTQt will translate it to an array reference containing all the object's strings. In the other way, instead of providing a TQt::StringList object as an argument of a method, one would simply provide the reference to an array of Perl strings. Here is the list of Marshallers as of PerlTQt-3.008 : ----------------------------------------------------------------- float, double <=> Perl real (NV) char, uchar, int, uint, enum long, ulong, short, ushort <=> Perl integer (IV) TQString, -&, -* => Perl string (utf8) TQString, -&, -* <= Perl string (utf8 or iso-latin1 or locale) TQCString, -&, -* <=> Perl string (utf8 or bytes, according to content or "bytes" pragma) TQByteArray, -&, -* <=> Perl string (bytes) TQStringList, -&, -* => Reference to an array of Perl strings (utf8) TQString, -&, -* => Perl string (utf8 or iso-latin1 or locale) int&, -* <=> Perl integer (IV) bool&, -* <=> Perl boolean char* <=> Perl string (bytes) char** <= Reference to an array of Perl strings (bytes) uchar* <= Perl string (bytes) TQRgb* <= Reference to an array of Perl integers (IV) TQCOORD* <= Reference to an array of Perl integers (IV) void* <=> Reference to a Perl integer (IV) TQValueList, - *, - & <=> Reference to an array of Perl integers (IV) TQCanvasItemList, - *, - & => Reference to an array of TQt::CanvasItem TQWidgetList, - *, - & <=> Reference to an array of TQt::Widget TQObjectList, - *, - & <=> Reference to an array of TQt::Object TQFileInfoList, - *, - & <=> Reference to an array of TQt::FileInfo TQPtrList, - *, - & <=> Reference to an array of TQt::Tab TQPtrList, - *, - & <=> Reference to an array of TQt::ToolBar TQPtrList, - *, - & <=> Reference to an array of TQt::NetworkOperation TQPtrList, - *, - & <=> Reference to an array of TQt::DockWindow (TQUObject*)