This article presents an object-oriented (OO) scripting interface for a legacy electronic structure code, specifically the Dacapo code, which is based on density functional theory (DFT). The interface allows users to interact with the code in a high-level, flexible manner without modifying the underlying numerical code. The authors discuss the design of the interface and the advantages of using a homogeneous interface. Object-oriented programming is widely used in computing, but its adoption in computational physics and chemistry has been limited. This is partly due to a focus on speed and a lack of attention to user interfaces. However, recent developments have enabled the separation of code into low-level numerical parts and high-level steering, making OO programming more feasible. The Dacapo code, developed at the Center for Atomic-scale Materials Physics (CAMP), is used to describe atomic system structure and dynamics. It calculates energy and forces acting on atoms and determines equilibrium structures or rates of atomistic-molecular processes. The code is written in Fortran 77 and has been modernized with Fortran 90 elements. It is still under development, with an emphasis on implementing the most up-to-date algorithms. The Dacapo code has a large number of input parameters, including structural information and technical parameters such as plane-wave cutoff, number of electronic bands, and exchange-correlation functional. The code uses the NetCDF file format for input and output, allowing users to create parameter files for simulations. The authors developed an OO interface to the Dacapo code using Python, which provides a high-level, flexible interface. This interface allows users to perform simulations, analyze results, and control the code in a more advanced way. The interface is built using Python modules that encapsulate the original code, making it easier to extend and integrate with other tools. The interface includes classes such as Simulation, ListOfAtoms, and ElectronicBands, which allow users to define simulations and parameters. The interface is designed to be flexible and extensible, allowing users to perform a wide range of tasks. The authors also discuss the importance of naming conventions in OO design, emphasizing the need for clear and descriptive names to ensure usability and maintainability. The interface is used to perform simulations, analyze results, and visualize data. The authors provide examples of how the interface can be used to perform calculations and plot results. The interface is also used to integrate with other codes, such as the EMT code, demonstrating the flexibility and power of the OO approach. The authors conclude that the OO interface provides a flexible and powerful way to interact with the Dacapo code, making it more accessible and easier to use for researchers. The interface is available for download and can be used by others to develop similar interfaces for their codes.This article presents an object-oriented (OO) scripting interface for a legacy electronic structure code, specifically the Dacapo code, which is based on density functional theory (DFT). The interface allows users to interact with the code in a high-level, flexible manner without modifying the underlying numerical code. The authors discuss the design of the interface and the advantages of using a homogeneous interface. Object-oriented programming is widely used in computing, but its adoption in computational physics and chemistry has been limited. This is partly due to a focus on speed and a lack of attention to user interfaces. However, recent developments have enabled the separation of code into low-level numerical parts and high-level steering, making OO programming more feasible. The Dacapo code, developed at the Center for Atomic-scale Materials Physics (CAMP), is used to describe atomic system structure and dynamics. It calculates energy and forces acting on atoms and determines equilibrium structures or rates of atomistic-molecular processes. The code is written in Fortran 77 and has been modernized with Fortran 90 elements. It is still under development, with an emphasis on implementing the most up-to-date algorithms. The Dacapo code has a large number of input parameters, including structural information and technical parameters such as plane-wave cutoff, number of electronic bands, and exchange-correlation functional. The code uses the NetCDF file format for input and output, allowing users to create parameter files for simulations. The authors developed an OO interface to the Dacapo code using Python, which provides a high-level, flexible interface. This interface allows users to perform simulations, analyze results, and control the code in a more advanced way. The interface is built using Python modules that encapsulate the original code, making it easier to extend and integrate with other tools. The interface includes classes such as Simulation, ListOfAtoms, and ElectronicBands, which allow users to define simulations and parameters. The interface is designed to be flexible and extensible, allowing users to perform a wide range of tasks. The authors also discuss the importance of naming conventions in OO design, emphasizing the need for clear and descriptive names to ensure usability and maintainability. The interface is used to perform simulations, analyze results, and visualize data. The authors provide examples of how the interface can be used to perform calculations and plot results. The interface is also used to integrate with other codes, such as the EMT code, demonstrating the flexibility and power of the OO approach. The authors conclude that the OO interface provides a flexible and powerful way to interact with the Dacapo code, making it more accessible and easier to use for researchers. The interface is available for download and can be used by others to develop similar interfaces for their codes.