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Re: namespace support?

From: Leo Singer
Subject: Re: namespace support?
Date: Sun, 7 Feb 2010 00:29:18 -0800

Sorry, I forgot to cc the list on this.

How about the following import.m?  Although I have not been able to
try it on the development version yet, it should work provided that
function handles off the path are supported.  In a function that you
want to use just add

import mypackage

to bring all the functions in the "+mypackage" directory (anywhere on
the path) into the local scope

import mypackage.myfunction

to bring in just the function declared by "+mypackage/myfunction.m".


function import(varargin)
 error(nargchk(1, inf, nargin, "struct"));
 for i=1:nargin
   [names, funcs] = import1(varargin{i});
   for j=1:length(names)
     assignin("caller", names{j}, funcs{j});

function [names, funcs] = import1(pkgname)
 pkgname_parts = strsplit(pkgname, ".");
 if length(pkgname_parts) > 2
   error("invalid package name: %s", pkgname);
 pkgpath = locatepkg(pkgname_parts{1});
   cwd = pwd;
   names = what(pwd);
   names = {names.m{:}, names.mex{:}, names.oct{:}};
   names = cellfun(@stripExtension, names, "UniformOutput", false);
   if length(pkgname_parts) == 2
     if any(strcmp(pkgname_parts{2}, names))
       names = {pkgname_parts{2}};
       error("function `%s' not found in package `%s'", ...
         pkgname_parts{2}, pkgname_parts{1});
   funcs = cellfun(@str2func, names, "UniformOutput", false);

function pkgpath = locatepkg(pkgname)
 pathdirs = strsplit(path, pathsep);
 for iPath=1:length(pathdirs)
   pkgpath = [pathdirs{iPath} filesep "+" pkgname];
   if exist(pkgpath, "dir")
 error("package `%s' cannot be located in the path", pkgname);

function fileName = stripExtension(fileName)
 dotIndices = strfind(fileName, ".");
 fileName = fileName(1:(dotIndices(end)-1));

On Sat, Feb 6, 2010 at 9:13 PM, Jaroslav Hajek <address@hidden> wrote:
> On Sun, Feb 7, 2010 at 1:45 AM, Leo Singer <address@hidden> wrote:
>> One could almost write an M-file function called "import" to implement
>> this in Octave without modifying the interpreter.
>> It might work by creating function handles to functions that are not
>> on the path.  However, attempting to invoke a function handle that
>> points to an M-file that is no longer on the path results in the
>> following error message:
>> error: invalid function handle
>> Matlab does support function handles to functions that are no longer
>> on the path.  How hard would it be to implement this in Octave?
>> Leo Singer
> No, this is not true in the development version:
> lt-octave:1> a = @somefunc
> a =
> @somefunc
> lt-octave:2> a()
> somefunc
> lt-octave:3> cd ..
> lt-octave:4> a()
> somefunc
> But I think that "import" will be very easy once the support for the
> package lookup will be done. My idea is that calling just the name
> "package_name" will return a special "package" object, much like class
> constructors do, that can be further indexed to get functions or
> classes (because Octave allows this and always did).
> This will even enable us to do
> local_name = package_name;
> local_name.package_func ()
> The problem seems to be with function handles.
> In any case, I won't work on it prior to 3.4.0 release, and I'm not
> even sure it is a good idea given that I have no access to a Matlab
> copy having this feature. So maybe someone else will have to do it.
> --
> RNDr. Jaroslav Hajek, PhD
> computing expert & GNU Octave developer
> Aeronautical Research and Test Institute (VZLU)
> Prague, Czech Republic
> url:

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