vaidation.py

# Copyright (c) 2009 Metanational Commons Ltd.

from time import time
from sha import new as sha1

CO_VARARGS = 4
CO_VARKEYWORDS = 8

def validate(**spec):

    def __decorate(func):

        rkey = sha1(str(time())).hexdigest()[:8]
        rkw = 'kw_%s' % rkey

        code = func.func_code
        varnames = list(code.co_varnames)
        defaults = func.func_defaults or ()

        varargs = varkwargs = None

        if code.co_flags & CO_VARKEYWORDS:
            varkwargs = varnames.pop(-1)

        if code.co_flags & CO_VARARGS:
            varargs = varnames.pop(-1)

        params = [varnames.pop(0)]; add = params.append
        params2 = params[:]; add2 = params2.append
        default_pointer = len(varnames) - len(defaults)

        for idx, varname in enumerate(varnames):
            if idx < default_pointer:
                add(varname)
                add2("%s[%r]" % (rkw, varname))
            else:
                add("%s=defaults_%s[%s]" % (varname, rkey, idx-default_pointer))
                add2("%s=%s.get(%r, defaults_%s[%s])" % (varname, rkw, varname, rkey, idx-default_pointer))

        if varargs:
            add("*%s" % varargs)
            add2("*%s[%r]" % (rkw, varargs))
        if varkwargs:
            add("**%s" % varkwargs)
            add2("**%s[%r]" % (rkw, varkwargs))
            
        params = ", ".join(params)
        params2 = ", ".join(params2)

        source = """
def newfunc(%(params)s):
    kwargs_%(r)s = locals()
    kw_%(r)s = {}
    for key_%(r)s in kwargs_%(r)s:
        if key_%(r)s in spec_%(r)s:
            kw_%(r)s[key_%(r)s] = spec_%(r)s[key_%(r)s](kwargs_%(r)s[key_%(r)s])
        else:
            kw_%(r)s[key_%(r)s] = kwargs_%(r)s[key_%(r)s]
    return func_%(r)s(%(params2)s)
""" % dict(params=params, params2=params2, r=rkey)

        print source

        env = {
            'func_%s' % rkey: func,
            'spec_%s' % rkey: spec,
            'defaults_%s' % rkey: defaults,
            }
        exec source in env

        return env['newfunc']

    return __decorate

@validate(a=float, b=str, c=int)
def foo(ctx, a, b, c=3, d=4, **kwargs):
    print "a:", `a`
    print "b:", `b`
    print "c:", `c`
    print "d:", `d`
    print "kwargs:", `kwargs`

def foo2(ctx, a, b, c=3, d=4, **kwargs):
    print "a:", `a`
    print "b:", `b`
    print "c:", `c`
    print "d:", `d`
    print "kwargs:", `kwargs`

@validate(a=float, b=str)
def bar(ctx, a, b, *args, **kwargs):
    print
    print "a:", `a`
    print "b:", `b`
    print "args:", `args`
    print "kwargs:", `kwargs`
    print

@validate(a=float, b=str)
def spam(ctx, a, b, *args):
    print
    print "a:", `a`
    print "b:", `b`
    print "args:", `args`
    print

@validate(a=int, b=str)
def blah(ctx, a, b):
    print
    print "a:", `a`
    print "b:", `b`
    print


@validate(a=float, b=str, c=int)
def yam(ctx, a, b, c=3, d=4, **kwargs):
    pass

def validate2(**spec):
    def __decorate(func):
        def __decorated(*args, **kwargs):
            return func(*args, **kwargs)
        return __decorated
    return __decorate

@validate2(a=float, b=str, c=int)
def yam2(ctx, a, b, c=3, d=4, **kwargs):
    pass

def yam3(ctx, a, b, c=3, d=4, **kwargs):
    pass

foo(None, 20, 'hello', 4, 33, random='foo')

bar(None, 20, 'hello', 4, 33, random='foo')

spam(None, 20, 'hello', 4, 33, 'foo')

blah(None, 20, 'hello')

start = time()
for i in xrange(10000):
    yam(None, 20, 'hello', 4, 33, random='foo')
end = time()

start2 = time()
for i in xrange(10000):
    yam2(None, 20, 'hello', 4, 33, random='foo')
end2 = time()

start3 = time()
for i in xrange(10000):
    yam3(None, 20, 'hello', 4, 33, random='foo')
end3 = time()

print "Native:", end3 - start3
print "Decorated:", end2 - start2
print "Validated:", end - start
print "Multiplier:", (end - start) / (end2 - start2)