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pyffi

An interface to the Python programming language.

Usage

(require-extension pyffi)

Documentation

The pyffi extension uses the Python C interface to invoke Python procedures and methods from within Scheme and to convert data objects between their Python and Scheme representation.

Currently, pyffi supports the Python data types listed in the table below. All other Python data types are represented as pointers.

int, floatnumeric types, converted to and from the corresponding Scheme numeric values.
listlist type, converted to and from Scheme list value
strstring type, converted to and from Scheme string value
unicodeUnicode string type, converted to and from Scheme utf8 string
dictdictionary type, converted to and from Scheme alist value
instanceclass instance type, converted to Scheme alist value
tupletuple type, converted to and from Scheme vector value

Installation

The setup script of pyffi attempts to autodetect the location of the Python header files and libraries for Python versions 2.3-2.7. The autodetection routine checks some standard installation locations for Linux, Mac OS X, and Windows. If autodetection fails, you may also specify the header and library locations as follows:

PYTHON_CFLAGS=-I/usr/include/python2.6 PYTHON_LFLAGS=-L/usr/lib PYTHON_LIBS=-lpython2.6 chicken-install pyffi

Procedures

py-startprocedure

Initializes the Python interpreter, and creates an evaluation environment. This procedure must be called before all other procedures in the extension.

py-stopprocedure

Deallocates the memory reserved by the Python interpreter, and frees all internal structures of the extension.

py-import nameprocedure

Imports Python module NAME. If the import was unsuccessful, raises an exception of type 'pyerror.

py-eval exprprocedure

Evaluates the Python expression contained in the string EXPR and returns the resulting value, either converted to Scheme representation, or as a pointer to a Python value.

py-apply func arg1 ...procedure

Applies the given arguments to the Python object FUNC and returns the resulting value, either converted to Scheme representation, or as a pointer to a Python value. The arguments must be either Scheme values of types listed in the type conversion table above, or pointers to Python values.

Macros

(define-pyfun expr arg1 ...)syntax

Defines a Scheme procedure named when called, invokes the Python procedure of the same name. EXPR is either a string that contains the procedure name, or a pair of the form (FORM . NAME) where FORM is a Python expression that when evaluated returns a Python procedure, and NAME is a string that contains the name of the Scheme procedure. The arguments must be all symbols.

(define-pyslot NAME [SCHEME-NAME])syntax

Defines an accessor/modifier for the Python object attribute NAME. The optional argument SCHEME-NAME is an alternate name for the Scheme procedure. The returned procedure takes in a Python object and returns the value of attribute NAME contained in that object. If the object has no such attribute, #f is returned. If a value is supplied after the name of the object, the procedure acts as a modifier for that slot.

(define-pymethod NAME [SCHEME-NAME: NAME] [KW: NAME-LIST])syntax

Defines an accessor for the Python method NAME. The optional keyword argument SCHEME-NAME is an alternate name for the Scheme procedure. The optional keyword argument KW is a list of keyword argument names for the Python method. The accessor is a procedure of the form LAMBDA OBJ ARG1 ... that takes in a Python object OBJ and invokes the method NAME contained in that object, with the supplied arguments, which must be either Scheme values of types listed in the type conversion table above, or pointers to Python values. If the object has no such method, #f is returned.

Examples

(import chicken)
(require-extension pyffi)

(py-start)

(py-import "h5py")
(py-import "numpy")


(define-pyfun "h5py.File" name mode)
(define-pymethod "close") ;; File
(define-pymethod "create_dataset" kw: (dtype)) ;; File

(define-pyslot "shape")
(define-pyslot "dtype")
(define-pyslot "name")

(define f (h5py.File "mytestfile.hdf5" "w"))

(define dset (create_dataset f "mydataset"  (vector 100) dtype: "i"))

(print (py-object-from (name dset)))
(print (py-object-from (shape dset)))
(print (py-object-type (dtype dset)))

(close f)
 ;;
 ;; Python-UNO example from pyffi.lisp by Dmitri Hrapof.
 ;;
 ;; Before running the following code, you must make sure OpenOffice is
 ;; running as a server:
 ;;
 ;;  soffice "-accept=socket,host=localhost,port=2002;urp;"
 ;;
 (require-extension pyffi)
 
 (py-start)
 
 (py-import "uno")
 
 (define-pyfun "uno.getComponentContext")
 
 (define-pyslot "ServiceManager")
 (define-pyslot "Text")
 
 ;; Can't yet find out appropriate class, the following is lame
 (define-pymethod "createInstanceWithContext")
 (define-pymethod "resolve")
 (define-pymethod "getCurrentComponent")
 (define-pymethod "createTextCursor")
 (define-pymethod "insertString")
 
 (define (message-uno str)
   (let* ((lc (uno.getComponentContext))
 	 (resolver (createInstanceWithContext 
 		    (ServiceManager lc)
 		    "com.sun.star.bridge.UnoUrlResolver" lc))
 	 (ctx (resolve resolver "uno:socket,host=localhost,port=2002;urp;StarOffice.ComponentContext"))
 	 (desktop (createInstanceWithContext 
 		   (ServiceManager ctx)
 		   "com.sun.star.frame.Desktop" ctx))
 	 (model   (getCurrentComponent desktop))
 	 (text    (Text model))
 	 (cursor  (createTextCursor text)))
     (insertString text cursor str 0)))
 
 
 (message-uno "Hello, world!")
About this egg
Author
Ivan Raikov
Version history
3.3


added support for keyword arguments in method definitions
3.0


using bind instead of easyffi
2.18


setup script updated for Python 2.7 (thanks to Mario Domenech Goulart)
2.17


Documentation converted to wiki format
2.16


setup script updated for Python 2.6
2.15


Changed getattr to not convert return result to Scheme value
2.14


Eliminated dependency on matchable
2.13


More fixes in converting Python values to Scheme
2.12


Fixes in converting Python values to Scheme
2.11


Ported to Chicken 4


License
Copyright 2007-2016 Ivan Raikov. Based on pyffi.lisp by Dmitri Hrapof.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

A full copy of the GPL license can be found at
<http://www.gnu.org/licenses/>.




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