This is an issue where there are possible compromises. For example, Smalltalk has achieved success being an SDE where you can edit methods, but not the structur

This is an issue where there are possible compromises. For example, Smalltalk has achieved success being an SDE where you can edit methods, but not the structure of classes. This way, it is impossible to create invalid classes, but you can still edit methods inside the environment as if they were text files.