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@@ -1,112 +0,0 @@ - - Tcl for Pd - ========== - -This library allows to to write externals for Pd using the Tcl language. - -It is based on the standard API of PD (defined in m_pd.h, plus some other -private header files, like g_canvas.h, s_stuff.h, ...). - -Also a library of Tcl helper functions is provided. It is not mandatory to use -it (moreover: it requires Tcl 8.5, while the tclpd external alone requires only -Tcl 8.4), but it is a syntactic sugar and can simplify a lot the code. -Using it is as simple as sourcing pdlib.tcl in your Tcl external. - -Anyway, disregarding any approach chosen to develop Tcl externals, a general -knowledge of Pd internals (atoms, symbols, symbol table, inlets, objects) is -strongly required. (Pd-External-HOWTO is always a good reading) - - - Compiling and installing - ======================== - -To compile tclpd, simply type: - - make clean all - -To compile it with debug enabled: - - make DEBUG=1 clean all - -Requirements are pd >= 0.39, swig, c++ compiler. -To install tclpd, simply copy it to /usr/lib/pd/extra (or where you installed -pure-data). - - - Writing GUI externals - ===================== - -Pd is split into two processes: pd (the core) and pd-gui. -A simple pd external just runs in the core. A simple Tcl externals still runs -in the core, because tclpd creates a Tcl interpreter for that. - -Instead, pd-gui has its own Tcl interpreter. In order to to GUI things (i.e. -draw on the canvas, or react to mouse events), the core process needs to -communicate with the pd-gui process (generally sending Tk commands, or calling -procedures defined in the pd-gui interp. -This is done with the sys_gui() function, if using the plain API. - -Also pdlib.tcl provide means to simplify this task, with the guiproc function, -which defines procedures directly into the pd-gui interpreter. - -As a counterexample, I'd like to cite tot/toxy/widget externals, which you may -be familiar with. -Such externals run in the pd-gui process. That was fine for writing simple gui -externals, that don't need to react to any message. -But, for instance, you cannot do a metronome or anything which is timing -accurate, or heavy IO, as that is not the purpose of the gui process. -Tclpd instead, by running in the core process, allows that. - - - Data conversion between Tcl <=> Pd - ================================== - -In pd exists 'atoms'. An atom is a float, a symbol, a list item, and such. -Tcl does not have data types. In Tcl everything is a string, also numbers and -lists. Just when something needs to be read as number, then evaluation comes -in. -This leads to loss of information about atom types. Imagine a -symbol '456' comes into tclpd, you won't know anymore if "456" -is a symbol or a float. - -Here a little convention comes in: in tclpd an atom gets converted into a -two-item list, where first item is atom type, and second item is its value. - -Some examples of this conversion: - - Pd: 456 - Tcl: {float 456} - - Pd: symbol foo - Tcl: {symbol foo} - - Pd: list cat dog 123 456 weee - Tcl: {{symbol cat} {symbol dog} {float 123} {float 456} {symbol wee}} - - - Examples - ======== - -I provided small examples. -after loading pd with option '-lib tcl', just type the filename -(minus the .tcl extension) to load the Tcl externals examples. - -actually there is one simple example: list_change (behaves like -[change] object, but work with lists only) - -examples make use of pdlib.tcl. It's still possible to port the example to use -only the plain Pd api. Contributions are welcome. - - - Authors - ======= - -Please refer to AUTHORS file found in tclpd package. - - - License - ======= - -Please refer to COPYING file found in tclpd package. - - |