Standardise on class constructor methods for object creation from different formats

[connortann]

I propose we use class constructor methods for all methods that instantiate objects from external input formats. This is a common "pythonic" pattern: see for example pd.DataFrame.from_dict(), pd.DataFrame.from_records().

Andy & I have been trying to roll out this pattern across resqpy, but currently we're a bit inconsistent and many classes need to be refactored. It is already implemented in a number of classes, for example resqpy.well.DeviationSurvey.from_data_frame .

How constructor methods are called by users

Class methods are called from the class directly, without first having to instantiate an object:

# Good
survey1 = DeviationSurvey.from_data_frame(df=df)
survey2 = DeviationSurvey.from_ascii_file(path="file.dat")

This is cleaner than first instantiating a messy "empty" object, and then calling another method to populate the attributes:

# Not as good
survey = DeviationSurvey(data=None)
survey.from_data_frame(df)

Rationale

• The init method becomes simpler: does not need any logic relating to file formats, makes it clearer what are the important data attributes
• Init method can assume data is actually given when class is created: can do validation, type checking et cetera in one place.
• Each constructor method is completely independent, the loading is done before the object is instantiated.

Example implementation

class DeviationSurvey:

    def __init__(self, data):
       # Arguments are the fundamental data needed to instantiate the class
        self.data = validate_inputs(data)    # Data is a mandatory attribute
    
    @classmethod
    def from_file(cls, file):
        with open(file) as f:
            data = f.read()
        return cls(data=data)  # This calls the init method

Checklist

• DeviationSurvey
• Polyline
• Property
• TetraGrid
• Use class constructor methods for PointSet #305
• Implement a class method for Surface from fault sticks #158
• Use class constructor methods in PolylineSet #167
• Use class constructor methods for Trajectory #303