Strategy Pattern example

gistfile1.py

def not_empty_string(value):
    assert(len(value) > 0)

def valid_email(value):
    assert("@" in value)

def greater_than_zero(value):
    assert(int(value) > 0)

FIELD_VALIDATORS = {
    "name": not_empty_string,
    "email": valid_email,
    "age": greater_than_zero
}

def validate_form(form):
    for field in form.fields:
        FIELD_VALIDATORS[field.name](field.value)