php application class structure guidelines -

i developing php application using mvc architecture , need suggestions following design guidelines:

according php class structure best practises, noted should minimize module dependencies, application class inheritance followed:

• some operations/methods accessible classes
• what have done have created helperclass contain these "global" methods string manipulations, integer manipulations, array manipulations , let other classes use these methods extend class.

class organization:

interface stringhelper{  ... } interface arrayhelper{  ... }  class generalhelper implements stringhelper, arrayhelper{  ...... }  class newclass extends generalhelper{  ... }  // user factory style create object class newclassfactory{   public function create( $options ){     return new newclass( $options );     } } 

the application has 15 classes.

is approach suitable scenario or end having big issues when maintaining application? appreciate help.

in cases helper classes should static , no working class should extend it. helpers global , have no role in main scope of working class. think of helpers plumbers, handymen etc . if writing family class shouldn't extend plumbers, plumbers should come in when needed , out no relation whatsoever family.

what need this:

class newclass {  ... $some_string = declaration  $some_string = stringhelper::sanitizestring($some_string);  }