如何在 python 中准确获取 lambda 函数的代码？

Question

I would like to know if there is a way to get the code of the following lambda functions:

a = {"test": lambda x: x + 123, "test2": lambda x: x + 89}

Is there a way to like

print(getsource(a["test"])

That returns :

lambda x: x + 123

I'm already aware of inspect and dill getsource functions but the following code:

import inspect
import dill

if __name__ == "__main__":

    a = {"test": lambda x: x + 123, "test2": lambda x: x + 89}

    print(inspect.getsource(a["test"]))
    print(dill.source.getsource(a["test"]))

Returns:

a = {"test": lambda x: x + 123, "test2": lambda x: x + 89}

a = {"test": lambda x: x + 123, "test2": lambda x: x + 89}

Answer 1

I ran into the same problem so I wrote a few code that I believe can at least partially address this.

def get_lambda_source(lambda_func, position):
    import inspect
    import ast
    import astunparse
    code_string = inspect.getsource(lambda_func).lstrip()
    class LambdaGetter(ast.NodeTransformer):
        def __init__(self):
            super().__init__()
            self.lambda_sources = []

        def visit_Lambda(self, node):
            self.lambda_sources.append(astunparse.unparse(node).strip()[1:-1])

        def get(self, code_string):
            tree = ast.parse(code_string)
            self.visit(tree)
            return self.lambda_sources
    return LambdaGetter().get(code_string)[position]

In your case,

print(get_lambda_source(a['test'], 0]))

returns

lambda x: x + 123

Note this doesn't work in the shell.

Answer 2

How about the following function mygetsource ?

import inspect

def mygetsource(l, n):
    s = inspect.getsource(l[n])
    s = s[s.index('{')+1:-2]
    d = {x[1:x.index(':')-1]: x[x.index(':')+2:] for x in s.split(', ')}
    return d[n]

a = {"test": lambda x: x + 123, "test2": lambda x: x + 89}
print(mygetsource(a, "test"))
print(mygetsource(a, "test2"))
b = {'func1': lambda y: y * 10, 'func2': lambda z: z ** z}
print(mygetsource(b, "func1"))
print(mygetsource(b, 'func2'))

Below is the result:

lambda x: x + 123
lambda x: x + 89
lambda y: y * 10
lambda z: z ** z