from functools import wraps

def boolean(value, field):

    t=[True,"true",1]

    f=[False,"false",0]

    if value in t:

        return True

    elif value in f:

        return False

    else:

        raise ValidateException(field=field, msg='%s is not boolean' % field)

def validateHash(value,field,minlength=None,maxlength=None):

    if not re.match(r'^[a-f0-9]*$', value.lower()):

    if minlength and len(value)<minlength:

        raise ValidateException(field=field)

    if maxlength and len(value)>maxlength:

        raise ValidateException(field=field)

    return value

def vuserhash(value,field):

    '''vailidate function for userhash'''

    return validateHash(value,field,minlength=15,maxlength=15)

def validate(kwd,func, need=True,*args,**kargs):

        @validate(kwd=userhash, func=vuserhash)

    that will validate usrhash with the function vuserhash.

        @wraps(f)

            kp=getcallargs(new_f.original,*a,**k)

            try:

                if need or kp[kwd] is not None:

                    kp[kwd] = func(kp[kwd],kwd,*args,**kargs)

                else:

                    kp[kwd] = None

            except KeyError:

                if need:

                    raise ValidateException(field=kwd,msg="%s is nessasary"%kwd)

            return f(**kp)

        try:

            new_f.original=f.original

        except AttributeError:

            new_f.original=f