Source code for decorators

# labtools, Copyright (C) 2017 Jerry Fowler and Paul Scheet.
# This program comes with ABSOLUTELY NO WARRANTY. It is licensed under
# GNU GPL Version 3. License and warranty may be viewed in the manual.
'''
Some decorators I expect to use regularly
'''
import os
import sys

from labtools import const
from labtools import labexceptions


def abstractmethod(method):
    '''Declare a method 'abstract' in something vaguely like the java sense
    for an abstract class or interface. Usage:
>>>    @abstractmethod
>>>    def method_to_be_declared_abstract(): pass
    '''
    def default_abstract_method(*args, **kwargs):
        raise NotImplementedError('call to abstract method ' + repr(method))

    default_abstract_method.__name__ = method.__name__
    
    return default_abstract_method


def progress_bar_runner(function, counter=0, linewidth=100, perdot=1, stream=sys.stderr):
    """
    Decorate the execution of a loop with printed dots to indicate progress

    *function* is a method that returns a boolean to indicate whether or not to
    continue. Standard while-loop semantics apply. True means continue, False means stop.
    """
    if perdot < 1 or linewidth < 1:
        raise labexceptions.ProgrammingFlawWarning('perdot={}, linewidth={}. Both must be positive'.
                                                  format(perdot, linewidth))
    linemodulus = linewidth*perdot
    thisdict = dict({
            'perdot' : perdot,
            'linemodulus' : linemodulus,
            'counter' : counter
            })
    def _progress_bar(_dict_=thisdict, *args, **kwargs):
        result = function(*args, **kwargs)
        _dict_['counter'] += 1
        thiscounter = _dict_['counter']
        if not (thiscounter % _dict_['perdot']):
            stream.write(const.DOT)
            if not (thiscounter % _dict_['linemodulus']):
                stream.write(const.NEWLINE)
        return result
        

    return _progress_bar