如何获取由exec加载的任意变量，并在函数中使用它们

Question

我期待在Codeacademy上撰写基础生物信息学课程。他们有一个很好的编写课程的界面，但测试有点慢，因为必须保存，然后预览，然后运行。

所以我想写一个模拟他们的小测试环境。它的工作原理是将用户输入的代码作为字符串读入到函数中，代码中的所有str实例都被转换为unicode（我刚刚使用过正则表达式），然后使用exec 。

棘手的部分似乎是当我想要合并Submission Test。

提交测试需要返回True,False或str，并写成函数的主体。因此，例如：

的什么，我希望做一个简化版本：

# The submission test must be a function. 
def test_code(code, CC, error): 
    # Use information from errors in student code 
    if error: 
     return "Yada yada %s" %error 

    # Use information in the raw student code 
    if len(code.split("\n")) is not 2: 
     return "This should be accomplished in 2 lines" 

    # Have direct access to variables from the student code 
    # I'd like to avoid params['y'] if possible. 
    try: 
     y 
    except NameError: 
     return "Please use the variable y" 

    if y is not 8: 
     return "Wrong! Check stuff" 

    # Use information from print output 
    if str(y) not in CC: 
     return "Remember to print your variable!" 

    return True 

# Read in student code 
student_code = """y = 8 
        print y 
        potato""" 

# Catch print output 
CC = StringIO.StringIO() 
sys.stdout = CC 

# Execute student code and catch errors 
try: 
    exec student_code 
except Exception as e: 
    error = e 

# Start outputting to the terminal again 
sys.stdout = sys.__stdout__ 

# Run the submission test 
submission_test = test_code(student_code, CC.split("\n"), error) 

# Output the result of the submission test 
if submission_test is True: 
    print("Well done!") 
elif submission_test is False: 
    print("Oops! You failed... Try again!") 
else: 
    print(submission_test) 

不过，我似乎无法从exec code获得通过变量传递给提交测试功能（test_code在这种情况下）。

我可以在提交测试中执行代码，但是如果可能的话我想避免这种情况，否则它将不得不被添加到每个测试中，这看起来好像没有问题！

任何帮助，将不胜感激:)

Answer 1

好了，我的同事想通这一个。

它使用Devin Jeanpierre的答案的元素。

我们使用exec code in dictionary方法，然后将字典传入检查函数，然后在检查函数中，我们将字典解压到globals()。

# The submission test must be a function. 
def test_code(code, CC, error, code_vars): 

    # unpack the student code namespace into the globals() 
    globs = globals() 
    for var, val in code_vars.items(): 
     globs[var] = val 

    # Use information from errors in student code 
    if error: 
     return "Yada yada %s" %error 

    # Use information in the raw student code 
    if len(code.split("\n")) is not 2: 
     return "This should be accomplished in 2 lines" 

    # Have direct access to variables from the student code 
    # I'd like to avoid params['y'] if possible. 
    try: 
     y 
    except NameError: 
     return "Please use the variable y" 

    if y is not 8: 
     return "Wrong! Check stuff" 

    # Use information from print output 
    if str(y) not in CC: 
     return "Remember to print your variable!" 

    return True 

# Read in student code 
student_code = """y = 8 
        print y 
        potato""" 

# Catch print output 
CC = StringIO.StringIO() 
sys.stdout = CC 

# create the namespace for the student code 
code_vars = {} 

# Execute student code and catch errors 
try: 
    # execute the student code in the created namespace 
    exec student_code in code_vars 
except Exception as e: 
    error = e 

# Start outputting to the terminal again 
sys.stdout = sys.__stdout__ 

# Run the submission test 
submission_test = test_code(student_code, CC.split("\n"), error, code_vars) 

# Output the result of the submission test 
if submission_test is True: 
    print("Well done!") 
elif submission_test is False: 
    print("Oops! You failed... Try again!") 
else: 
    print(submission_test) 

Answer 2

如果exec mystr in somedict，然后somedict具有的mystr执行的Python代码时指定每个变量的引用。另外，你也可以用这种方式传递变量。

>>> d = {'y': 3} 
>>> exec "x = y" in d 
>>> d['x'] 
3 

您需要将您从运行的用户代码得到了词典，以便提交校验码可以验证值它是适当的。

Answer 3

这听起来像你想要code和test运行在相同的环境。两者都被提交为字符串，所以也许最简单的方法是连接两者，合并的字符串上运行exec：

from __future__ import unicode_literals 

def wrap_body(body): 
    indent = ' '*4 
    return 'def test():\n' + indent + body.replace('\n','\n'+indent)  

code = ''' 
bool_1 = True 
bool_2 = False 

str_1 = 'Hello there!' 
str_2 = "I hope you've noticed the apostrophe ;)" 
''' 

code_test = ''' 
try: 
    bool_1, bool_2, str_1, str_2 
except NameError: 
    return "Please do not alter the variable names!" 

if (bool_1 == bool_2 or str_1 == str_2): 
    return "Please ensure that all of your variables are different " \ 
      "from one another" 

if type(bool_1) != bool: return "bool_1 is incorrect" 
if type(bool_2) != bool: return "bool_2 is incorrect" 
if type(str_1) != unicode: return "str_1 is incorrect" 
if type(str_2) != unicode: return "str_2 is incorrect" 

return True 
''' 
code_test = wrap_body(code_test) 
template = code + code_test 
namespace = {} 
try: 
    exec template in namespace 
    print(namespace['test']()) 
except Exception as err: 
    print(err)