It so happens that you are given a project specs and your knowledge about the language is very basic. There are features in the project that you have never worked with. But you have some ideas and logic on how this can be implemented.  

Later on as the development continues you discover that the required features cannot be developed because of some language limitations or any other issues. Now you have to convince your client about this, which is not easy. 

**Edit**: the reason for working with not so comfortable technology is that,Company at times cannot afford to hire someone for this task. Hence relies on existing employees to learn something new and contribute.

So how do I avoid such situations? How do I research about the features before accepting the project ?