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Re: libseed-list Hooking into the imports system

Sure, defineObject() might be more in line with the current standard, even though I think the methods should be named getProperty and setProperty or something like that. ('get' and 'set' fields in defineProperty() already refers to Property while in this case we define an Object, not a property)
But, it's a little bit more work to wrap it in a function like defineObject() since I now simply use the existing C-side JS-class creation mechanism.. Do you think it would be worth it? 

/Jonatan

Alan Knowles wrote:

Do you think it would be an idea to copy the nearest standard here for your 'autoprop' Object. ?

https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Object/defineProperty

var o = imports.autoprop.defineObject({
    get : function (name) {

    },
    set : function (name, value) {

    },
    enumerable: function(name) {
       ...
    }

});

Regards
Alan
--- On 02/Jul/2010, Jonatan Liljedahl wrote:
Yes, this was a nice solution. See attached 'autoprop' module. (Feel free to include it in the main distro, I think it can be very useful for all sorts of special objects. Perhaps one should also add callbacks for CallAsFunction, CallAsConstructor, GetPropertyNames, etc..) 

With this I could simply do a custom module-importer object like this:

var make_importer = function(startPath, chain) {
     var o = new imports.autoprop.Object;

     o.get_property = function(name) {
         if(name==="searchPath") return imports.searchPath;
         var searchPath = startPath || imports.searchPath;

         for(var i=0;i<searchPath.length;i++) {
             var path = searchPath[i];
             var file = path+'/'+name;
             var file_als = file+'.als';

             if(_module_imports[file])
                 return _module_imports[file];

             if(GLib.file_test(file,GLib.FileTest.IS_DIR)) {
return _module_imports[file] = make_importer([file],chain.concat(name)); 
             } else
             if(GLib.file_test(file_als,GLib.FileTest.IS_REGULAR)) {
                 GLib.file_get_contents(file_als,script={});
                 ctx = new Context;
                 ctx.global.__script_path__ = path;
                 ctx.eval(script.contents);
                 return _module_imports[file]=ctx.global;
             }
         }
         // fall back to original seed imports
         for(var i=0,ns=imports;i<chain.length;i++)
             ns = ns[chain[i]];
         return ns[name] || null;
     }

     o.set_property = function(name, value) {
         if(name === "searchPath") {
             imports.searchPath = value;
             return true;
         }
         return false; //or true to not allow custom props to be set..
     }

     return o;
}

var module = make_importer(undefined, []);

// then I can use 'module' instead of 'imports' and it works exactly
// the same except it also handles my algoscript modules:

var Gtk = module.gi.Gtk;
var foo = module.mydir.mysubdirfoo;

/Jonatan

Jonatan Liljedahl wrote:

I don't see how this would be solved easily..
if 'xxx' is my magic handler, then autoloader can create an object 'xxx' that calls my handler on get_property().. so my handler would be called with 'zzzz'. Let's say 'zzzz' is a folder, and I want xxx.zzzz.foo to load the file foo from that folder.. Nothing I can return from a javascript handler would allow 'foo' to be fetched unless it's already an existing member of 'zzzz', since there's no Object.prototype.__lookupProperty__ hook or similar.
Maybe one could make a generic 'dynamic object' class in C, which could be used recursively... 

auto = new imports.dynamic.Object;
auto.get_prop = function(prop) {
  var x = my_lookup(prop,base);
// if x is dir, return a new dynamic Object with a handler for that directory.. 
//  if x is a file, parse and return namespace..
//  etc...
};

/Jonatan

Alan Knowles wrote:

It sounds alot like the autoload feature that was added to PHP.
It was only after the feature was made available that everyone realized that it was a flawed design (by that time people had already started using it...)
The partial solution was to add SPL::autoload() which does solve some of the problems.. 

for seed it might be that we have something like

imports.autoloader.register('xxx', function(args) {....});
or
imports.autoloader.register('xxx', imports.xxx.importer);

ZZZ = imports.autoloader.xxx.zzzz
That should give you the syntax you are after, without making it too confusing, along with enabling multiple handlers to be defined.. 

autoloader could easily be implemented in a very simple module...

Regards
Alan



 --- On 30/Jun/2010, Jonatan Liljedahl wrote:

Alan Knowles wrote:
My concern here is that this would make code very difficult to understand.
Is there a way to implement this where it is an explicit behavior rather than an implicit, Hence, when it is being used, you know from the syntax that it may be trying to do 
 > something magical, rather than overloading the 'reasonably'
 > predictable behavior of imports.
I think that would be up to the developer, to use the notFoundHandler in a wise way. My plan is mostly very 'reasonable', simply to add support for modules written in a custom language and not having to bother if a module is written in C, javascript, algoscript, or imported from GIR.
But I can see other (more or less reasonable) use cases too, creating virtual namespaces under imports to integrate with other stuff, and I think it would be a very elegant feature. 


or could this not be done client side?
eg.

imports.smartloader.load('xxx');
Yes, that's almost what I do now, I have an imports.algoscript.Importer class with a root instance at imports.algoscript._root_importer, so that I can do: 

zoo = imports.algoscript._root_importer._import('foo.bar.zoo');
But it means a lot of not-well-working duplication of the seed imports object, since I want to use it for both normal seed imports and also to handle directories the same was as seed imports does. (above should work if foo is a dir, bar a file and zoo a variable in that file)...
Also it looks very ugly, so I have created special syntactic sugar in algoscript to make it look like "zoo = import foo.bar.zoo".
The very nice thing with the imports object is that the properties are virtual (they are created/found on the fly), but that any "real" JS object in the chain simply takes over from there. You don't need to care what part is a directory, a file, or a variable in that file, or a member of an object in that file, etc.. This is not possible on client side, I'd have to write my own importer class in C for this, more or less duplicating everything from seed-importer.c...
But I'd really prefer to just use the existing system that's already there and does it the right way: then I could just have a single handler function, something like this: 

imports.__notFoundHandler__ = function(name,dir) {
     var dirs = [dir];
     var ns;
     if(dir!=imports.searchPath[0])
         dirs = dirs.concat(imports.searchPath);
     dirs.forEach(function(d) {
         if (d == '.' && __script_path__)
             d = __script_path__;
         var f = d+'/'+name+'.as';
         if (file_exist(f)) {
             var ctx = new algoscript.Context;
             ctx.eval_file(f);
             ns = ctx.global;
             ctx.destroy();
         }
     });
     return ns;
}



For the toString stuff, I guess that's needed only for this patch.
BTW i'll be offline tommorow till next week, unless I can get net access... 
offline, that sounds scary... ;)

see you later, thanks for the feedback!

/Jonatan


Regards
Alan


 --- On 30/Jun/2010, Jonatan Liljedahl wrote:
Here is a small patch that adds a feature that I'd be very happy to see. It allows one to hook into the imports system by defining a handler for 
when a module was not found. Example:

   imports.__notFoundHandler__ = function(name, dir) {
     print("making "+name);
     return {foo:123}
   }
   f = imports.foobar;
   print(f.foo);

running above file prints:

   making foobar
   123

This can be used to integrate all sorts of cool stuff with the imports
object. For example, the handler can iterate over imports.searchPath to 
find n+".html" and return an object representation of the DOM tree, or
parsing a custom language (hmmmm ;)), or perhaps even connect to an
online database of modules.. x = imports.seedgems.foo; -> updates foo
from an online repository, etc...
Currently it only passes the first path from seed_importer_search_dirs() as the second arg, at least this works for the case when the search is done inside a single directory, but I guess it would be better to just send the whole path GSList by converting it to a JS array. One could still work around it on the script side by merging the dir arg with imports.searchPath if dir != searchPath[0].
BTW, this patch also adds the toString and toValue hack to seed_importer_dir_get_property() so it doesn't call the handler saying that "toString" module wasn't found, etc.. 

/Jonatan

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