text: # -*- coding: utf-8 -*-
  import floppyforms as forms
  
  from django import forms as django_forms
  from django.conf import settings
  
  
  def errors_append(form, field_name, message):
      u'''
      Add an ValidationError to a field (instead of __all__) during Form.clean():
  
      class MyForm(forms.Form):
          def clean(self):
              value_a=self.cleaned_data['value_a']
              value_b=self.cleaned_data['value_b']
              if value_a==... and value_b==...:
                  formutils.errors_append(self, 'value_a', u'Value A must be ... if value B is ...')
              return self.cleaned_data
      '''
      assert form.fields.has_key(field_name), field_name
      error_list=form.errors.get(field_name)
      if error_list is None:
          error_list = django_forms.util.ErrorList()
          form.errors[field_name] = error_list
      error_list.append(message)
  