Let's say, I have a bunch of functions a
, b
, c
, d
and e
and I want to find out if they directly use a loop:
def a():
for i in range(3):
print(i**2)
def b():
i = 0
while i < 3:
print(i**2)
i += 1
def c():
print("\n".join([str(i**2) for i in range(3)]))
def d():
print("\n".join(["0", "1", "4"]))
def e():
"for"
I want to write a function uses_loop
so I can expect these assertions to pass:
assert uses_loop(a) == True
assert uses_loop(b) == True
assert uses_loop(c) == False
assert uses_loop(d) == False
assert uses_loop(e) == False
(I expect uses_loop(c)
to return False
because c
uses a list comprehension instead of a loop.)
I can't modify a
, b
, c
, d
and e
. So I thought it might be possible to use ast
for this and walk along the function's code which I get from inspect.getsource
. But I'm open to any other proposals, this was only an idea how it could work.
This is as far as I've come with ast
:
def uses_loop(function):
import ast
import inspect
nodes = ast.walk(ast.parse(inspect.getsource(function)))
for node in nodes:
print(node.__dict__)
A loop is a programming function that iterates a statement or condition based on specified boundaries. The loop function uses almost identical logic and syntax in all programming languages.
No, it is a keyword: a function is an object that transforms input in output. A for does not do that.
Just as a loop is an embodiment of a piece of code we wish to have repeated, a function is an embodiment of a piece of code that we can run anytime just by calling it into action. A given loop construct, for instance could only be run once in its present location in the source code.
You need to check if the function's Abstract Syntaxt Tree has any nodes that are an instance of ast.For
or ast.While
or ast.AsyncFor
. You can use ast.walk()
to visit every node of the AST
import ast
import inspect
def uses_loop(function):
loop_statements = ast.For, ast.While, ast.AsyncFor
nodes = ast.walk(ast.parse(inspect.getsource(function)))
return any(isinstance(node, loop_statements) for node in nodes)
See the documentation for ast
, async for
was added in 3.5.
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