Property, method, slot binders: eager and late

binders.js

// One-way property binders

function bindNowGetProp( propname, obj ) {
  return function() { return obj[propname]; }
}

function bindNowSetProp( propname, obj ) {
  return function(v){ return obj[propname] = v; }
}

function bindLaterGetProp( propname ) {
  return function( obj ) {
    return obj[propname];
  }
}

function bindLaterSetProp( propname ) {
  return function( obj, v ) {
    return obj[propname] = v;
  }
}

// Generic one-way property binders

function bindGetProp( propname, obj ) {
  return arguments.length < 2 
       ? bindLaterGetProp( propname ) :
       : bindNowGetProp( propname, obj );
}

function bindSetProp( propname, obj ) {
  return arguments.length < 2 
       ? bindLaterSetProp( propname ) :
       : bindNowSetProp( propname, obj );
}

// Slot binders

function bindNowSlot( propname, obj ) {
  return function(v) {
    return arguments.length<1 ? obj[propname] : obj[propname] = v;
  }
}

function bindLaterSlot( propname ) {
  return function(obj,v) {
    return arguments.length<2 ? obj[propname] : obj[propname] = v;
  }
}

// Generic slot binder

function bindSlot( propname, obj ) {
  return arguments.length<2 
       ? bindLaterSlot( propname ) 
       : bindNowSlot( propname, obj );
}

// Method binders (bindNowMethod only shown for completeness sake)

function bindNowMethod( propname, obj ) {
  return obj[propname].bind( obj );
}

function bindLaterMethod( propname ) {
  return function( obj ) {
    return obj[propname].apply( obj, Array.prototype.slice.call( arguments, 1 ) );
  }
}

// Generic method binder

function bindMethod( propname, obj ) {
  return arguments.length<2 
       ? bindLaterMethod( propname ) 
       : bindNowMethod( propname, obj );
}

// Technical: arg-list repackager

function appendArgs( prefix, args, from ) {
  Array.prototype.push.apply( prefix, Array.prototype.slice.call( args, from ) );
  return prefix;
}

// Re-bind to specific object and optional arguments (equivalent of Function.bind)

function bindNow( latebound /*...*/ ) {
  return Function.prototype.bind.apply( latebound, appendArgs( [null], arguments, 1 ) );
}

// Implementation of Eugene's lateBind()

function lateBind( object, name /*...*/ ) {
  return bindNow.apply( null, appendArgs( [ bindLaterMethod( name ), object ], arguments, 2 ) );
}