如何从文件中解析Python模块

Question

I saw this SO question and tried using it by creating a .py file with 2 methods and trying to read it.
The file:

def f1(a):
    print "hello", a
    return 1

def f2(a,b):
    print "hello",a,", hello",b

Trying to read it:

>>> r = open('ToParse.py','r')
>>> t = ast.parse(r.read)

Exception thrown:

Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
  File "C:\Python26\lib\ast.py", line 37, in parse
    return compile(expr, filename, mode, PyCF_ONLY_AST)
TypeError: expected a readable buffer object

What am I doing wrong?
My goal is to get a python module and be able to parse it using Python - expose its classes and methods.

Answer 1

You need to call read . So your line

t = ast.parse(r.read)

Should be

t = ast.parse(r.read())

See here for info on files and here for info on ast.parse

Answer 2

Use:

t = ast.parse(r.read()) # () is needed

Source: http://docs.python.org/2/tutorial/inputoutput.html#methods-of-file-objects

Answer 3

If you want to expose your classes and methods dynamically, then you probably need to use eval along with compile .

In this case you may do it like the following.

Create a file:

#test.py
def hello():
    print "hello"

And you can call it like this:

#main.py
testContent = open("test.py").read()
#evaluate a content
eval(compile(testContent, "<string>", 'exec'))
#call function
hello() #prints hello

EDIT : there is another way to evaluate file:

#main.py
#evaluate a content
eval(compile("import test", "<string>", 'exec')) #test.py
#check list of methods
dir(test) # ['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'hello']
#call function
hello() #prints hello

I do realize, that eval may be not that good choice, but I don't know other way. I'd glad to see other solution

Answer 4

You are trying to parse the function read on the file.

You want

t = ast.parse(r.read())

or (to more closely follow the example)

text = r.read()
ast.parse(text)

not

t = ast.parse(r.read)