class TableFormatter:

def headings(self, headers):

'''

Emit the table headings.

'''

raise NotImplementedError()

def row(self, rowdata):

'''

Emit a single row of table data.

'''

raise NotImplementedError()

class TextTableFormatter(TableFormatter):

'''

Emit a table in plain-text format

'''

def headings(self, headers):

for h in headers:

print(f'{h:>10s}', end=' ')

print()

print(('-'*10 + ' ')*len(headers))

def row(self, rowdata):

for d in rowdata:

print(f'{d:>10s}', end=' ')

print()

class CSVTableFormatter(TableFormatter):

'''

Emit a table in CSV format

'''

def headings(self, headers):

print(','.join(headers))

def row(self, rowdata):

print(','.join(rowdata))

class HTMLTableFormatter(TableFormatter):

'''

Emit a table in HTML format

'''

def headings(self, headers):

print('<tr>', end='')

for h in headers:

print(f'<th>{h}</th>', end='')

print('</tr>')

def row(self, rowdata):

print('<tr>', end='')

for d in rowdata:

print(f'<td>{d}</td>', end='')

print('</tr>')

class FormatError(Exception):

pass

def create_formatter(fmt):

'''

Factory function to create a formatter based on the specified format.

:param fmt: A string indicating the desired format ('txt', 'csv', 'html').

:return: An instance of a TableFormatter subclass corresponding to the specified format.

'''

if fmt == 'txt':

return TextTableFormatter()

elif fmt == 'csv':

return CSVTableFormatter()

elif fmt == 'html':

return HTMLTableFormatter()

else:

raise FormatError(f'Unknown table format: {fmt}')

def print_table(data, cols, formatter):

'''

Print a table of data using the specified format.

:param data: A list of stock objects containing the table data.

:param cols: A list of column names to be used as headings in the table.

:param formatter: A formatter object indicating the desired format (e.g. TextTableFormatter, ...)

'''

formatter.headings(cols)

for d in data:

rowdata = [str(getattr(d, colname)) for colname in cols] # ['AA', 100]

# rowdata = [str(item) for item in rowdata] # ['AA', '100']

formatter.row(rowdata)