Setter for class within a class : i have a Sheet class which contains two attributes and each is a class

1. summary (class)
2. data (class)

summary and data has 1 attribute,df, which is a dataframe

my question is, am i right to say that since summary and data are classes:
1. I shouldn't store summary and data directly as dataframes in Sheet class's attribute. 

2. I should store summary and data as objects and when main class wish to set summary/ data, i use Sheet's setter which uses summary/ data's setter to set the actual dataframe

Create sheet object in Main Class : 

```
import Sheet
sheet = Sheet.Sheet() # create empty sheet
sheet.set_summary(new_df) # set summary
sheet.set_data(new_df) # set data
```

In Sheet Class : 

```
import Summary
import Data

class Sheet:
    def __init__(self):
        self.name = None
        self._summary = Summary.Summary()
        self._data = Data.Data()

    def get_SheetSummary(self):
        return self._summary.get_summary()

    def set_SheetSummary(self,new_df):
        self._summary.set_summary(new_df)

    def get_SheetData(self):
        return self._data.get_data()

    def set_SheetData(self, new_df):
        self._data.set_data(new_df)
```