Why do Polymer's computed properties need explicit property arguments? -


i digging bit polymer 1.0 elements , little curious computed properties.

for example, in paper-drawer-panel.html,

<dom-module id="paper-drawer-panel" …>   …   <div id="main" style$="[[_computedrawerstyle(drawerwidth)]]">     …   </div>   … </dom-module> <script> polymer({   is: 'paper-drawer-panel',   …   _computedrawerstyle: function(drawerwidth) {     return 'width:' + drawerwidth + ';';   },   … </script> 

drawerwidth property of paper-drawer-panel, why important explicitly include in parameters of computed property?

is

[[_computedrawerstyle()]]  …  _computedrawerstyle: function () {   return 'width:' + this.drawerwidth + ';'; } 

is bad practice?

explicit arguments in computed bindings serve important purpose: telling polymer properties computed binding depends on. allows polymer know when recalculate , update computed binding.

take [[_computedrawerstyle()]], example. in case, polymer has no idea other properties computed binding depends on, , calculate once on load.

as add drawerwidth explicitly ([[_computedrawerstyle(drawerwidth)]]) polymer knows should run computed binding again new value every time drawerwidth changes.


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