from django import template
from django.template.defaultfilters import stringfilter

register = template.Library()

@register.filter(name='truncatechars')
@stringfilter
def truncatechars(value, arg):
    """
    Truncates a string after a certain number of chars.

    Argument: Number of chars to truncate after.
    """
    try:
        length = int(arg)
    except ValueError: # Invalid literal for int().
        return value # Fail silently.
    if len(value) > length:
        return value[:length] + '...'
    return value
truncatechars.is_safe = True