[FIXED] How to invoke a Python method using its fully qualified name?

Issue

In Java I can invoke a class or method without importing it by referencing its fully qualified name:

public class Example {
    void example() {

        //Use BigDecimal without importing it
        new java.math.BigDecimal(1);
    }
}

Similar syntax will obviously not work using Python:

class Example:
    def example(self):

        # Fails
        print(os.getcwd())

Good practice and PEP recommendations aside, can I do the same thing in Python?

Solution

A function does not exist until its definition runs, meaning the module it's in runs, meaning the module is imported (unless it's the script you ran directly).

The closest thing I can think of is print(__import__('os').getcwd()).

Answered By - Alex Hall

Answer Checked By - David Marino (PHPFixing Volunteer)

Read More

[FIXED] What could cause java.lang.reflect.InvocationTargetException?

Issue

Well, I've tried to understand and read what could cause it but I just can't get it:

I have this somewhere in my code:

 try{
 ..
 m.invoke(testObject);
 ..
 } catch(AssertionError e){
 ...
 } catch(Exception e){
 ..
 }

Thing is that, when it tries to invoke some method it throws InvocationTargetException instead of some other expected exception (specifically ArrayIndexOutOfBoundsException). As I actually know what method is invoked I went straight to this method code and added a try-catch block for the line that suppose to throw ArrayIndexOutOfBoundsException and it really threw ArrayIndexOutOfBoundsException as expected. Yet when going up it somehow changes to InvocationTargetException and in the code above catch(Exception e) e is InvocationTargetException and not ArrayIndexOutOfBoundsException as expected.

What could cause such a behavior or how can I check such a thing?

Solution

You've added an extra level of abstraction by calling the method with reflection. The reflection layer wraps any exception in an InvocationTargetException, which lets you tell the difference between an exception actually caused by a failure in the reflection call (maybe your argument list wasn't valid, for example) and a failure within the method called.

Just unwrap the cause within the InvocationTargetException and you'll get to the original one.

Answered By - Jon Skeet

Answer Checked By - Senaida (PHPFixing Volunteer)

Read More