osCommerce is one of those products that have been poorly designed from the very beginning and become almost invisible over time. Add-ons are patches, and custom code modifies the kernel. (Unless things have changed since the last time I looked at her - judging by the version numbers, they were not).
Although probably at a higher level than you seem to be asking, Drupal is a very attractive platform. This is a CMS at its base and with the help of ecommerce or Ubercart you can turn it into a store. With modules such as CCK and Views , you can create very complex e-commerce sites (specialized product types, attributes) with a very small number of encodings, and also get all CMS tools (editing, access control, etc.) for free. If you write your own modules, you can connect to almost anything in Drupal without touching the main code, and you get a lot of flexibility.
Although many developers may not take this into account simply because they are stuck with this idea that they need to write something from scratch, Drupal is really a great platform for developing these kinds of things. Of course, there is a certain learning curve for him, especially when you need to write modules for him, but the time taken to study and implement the site is still probably less than writing a custom e-commerce site from scratch.
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