OpenEuphoria

Re: New Language

• Posted by Mike Nelson <mikestar13 at sbcglobal.net> Sep 26, 2006
• 594 views

Pete Lomax wrote:

> Do you have any specs/design/examples? In particular side-by-side
> demos which extol the virtues, eg:
> OO:
> }}}
<eucode>
> 	return call_method(o,"length",{})
> </eucode>
{{{

> procedural:
> }}}
<eucode>
> 	if o[tag]=CAR then return o[CAR_LENGTH]
> 	elsif o[tag]=BOAT then return o[BOAT_LENGTH]
> 	...
> </eucode>
{{{

> Though obviously a bit more involved. Possibly start with the very
> first program you hope to get running and the coolest example you can
> think of that will only start working sometime nearer the release date
> perhaps with some example mods or bugfixes which are trivial in OO but
> fiddly and all over the place in the equivalent procedural code?
> 
> Not that I'm a particular fan of OO programming or anything...
> 
> Regards,
> Pete

We already have:

return call_method(o,"length",{})

this is the correct Method Euphoria syntax.

My new language will render it as the much more readable

return o.length()

There will still be support for the advantage of the former sytax: the method
name might be a variable, allowing indirect calling:

string x="length"
 	return System.call(o,x)

Here are two classes to whet the appetite while I'm working on the project:

class Container_Extension extends General_Container

General_Container base  

method shared Container_Extension new(General_Container base)
    Container_Extension me
    if base=nothing then throw Null_Reference.new() end if
    me=super()
    me.base=base
    return me
end method

method Container_Extension clone()
    Container_Extension me
    me=super()
    me.base=this.base.clone()
    return me
end method

method boolean base_is(type t)
    if this.base.is(Container_Extension) then
        return this.base.base_is(t) 
    else
        return this.base.is(t)
    end if
end method

method type base_type()
    if this.base.is(Container_Extension) then
        return this.base.base_type()
    else
        return this.base.type() 
    end if
end method

method protected call_failed(Exception reason,string name,array parameters)
    if reason.is(Undefined_Method) then
        System.call(this.base,name,parameters)
    else
        throw(reason)
    end if
end method

end class

class Locking_Container extends Container_Extension

public integer locked

method Locking_Container clone()
    Locking_Container me
    me=super()
    me.locked=false
    return me
end method

method integer insert(array parameters)
    if this.locked then
        throw Locked_Container.new()    
    else
        return super(paramters)
    end if
end method 

method any remove(array prameters)
    if this.locked then
        throw Locked_Container.new()    
    else
        return super(parameters)
    end if
end method 

method clear()
    if this.locked then
        throw Locked_Container.new()    
    else
        return super()
    end if
end method 

method lock()
    this.locked=true
end method

method unlock()
    this.locked=false
end method

end class

The Container_Extension class is a framework to facilitate the writing of
wrapper classes to add functionality to containers. The Locking_Container class
is a specific implementation--pass a Queue or a Map to its constructor and you
add the capabilty to lock and unlock the container. Only the methods which are
affected by locking are defined. Any other methods of the underlying container
result in the call_failed method bieng invoked with a Undefined_Method exception.
The call_failed method uses System.call to indirectly call the method on the
underlying container. This allows a kind of multiple inhertience or runtime
inheritence without all the problems of building it into the basic class
structure.