mardi 4 août 2015

Defining Symfony Services to maximize maintainability

I'm working on a big domain, for which maintainability is very important.
There are these general workers called ExcelHandlers that implement ExcelHandlerInterface (more on the interface in the ideas section) and basically get an UploadedFile as their input, upload them wherever they want and return the read data as an associative array. Now I have created this base class ExcelFileHandler which does all of these tasks for all excel files given two arguments:
1. The Directory to upload the file
2. the mapping of the excel columns to the indexes of the associative array.
Some ExcelHandlers might have to extend the ExcelFileHandler and do some more processing, in order to get the associative array of data.
The UploadedFile is always passed to the ExcelHandler from the controller.
Now here is the question. Given the generic structure of the ExcelFileHandler how should I define services for specific ExcelHandlers given that some only differ with the original one in the directory to upload the file and the mapping array.
My Ideas:


1. The first approach involves giving the directory and the mapping as the function arguments to ExcelHandleInterface::handle this will make the prototype something like handle(UploadedFile $file, array $mapping, $dir), $mapping and $dir are given to the function as arguments and passed to the handler by the controllers which has the parameters as constructor injections.


2.1 Defining the prototype of handle to be handle(UploadedFile $file), this would require the ExcelHandlers to have knowledge of $dir and $mapping. $dir will always be injected from the constructor. 2.1.1 Foreach individual ExcelHandler in the application, define a separate class e.g: UserExcelHandler, ProductExcelHandler, .... Which extend the ExcelFileHandler and leaves us again with two choices.
2.1.1.1 inject $mapping from outside. e.g:

// in the child class
public function __construct($dir, $mapping){
  parent::__construct($dir, $mapping);
}

2.1.1.2 define $mapping in the constructor of the child class. e.g:

// in the child class
public function __construct($dir){
  $mapping = array(0 => 'name', 1 => 'gender');
  parent::__construct($dir, $mapping);
}

2.1.2 Not to create a class for each separate ExcelHandler and instead define the ExcelFileHandler as an abstract service and decorate with the right parameters to get the concrete ExcelHandler Service with the desired functionality, obviously ExcelHandlers with custom logic must be defined seperately, and to create a uniform code base, $mapping will always be injected from the Container in this case.


In your experience, what other paths can I take and which ones yield better results in the long term?

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