如何在使用 VS Code Python 调试控制台时查看父作用域中的变量

Question

When I set a breakpoint in a function that is imported by another script, I would like to be able to view the variables that are in the parent scope from within the VS Code Python Debug Console. Is this possible, perhaps by modifying launch.json ?

Reproducible example:

I have two files, scratch_script.py and scratch_function.py . They exist in the same directory.

I place breakpoints where indicated by comments below.

Contents of scratch_script.py :

import scratch_function

parent_scope_var = 'I disappear'

scratch_function.scratch_function() # breakpoint on this line

pass # breakpoint on this line

Contents of scratch_function.py :

def scratch_function():
    child_scope_var = 'I appear'
    pass # breakpoint on this line

I run VS Code Python Debugger from scratch_script.py .

At the first break point, I can view parent_scope_var in the Python Debug Console, but not child_scope_var . So far so good.

When I proceed to the second break point, I can view child_scope_var , which is great. But now I cannot view parent_scope_var :

NameError: name 'parent_scope_var' is not defined

On the third breakpoint, the parent_scope_var is seen again in the Python Debug Console, but not the child_scope_var ... Which is as I would expect.

So, my only confusion is, why can't I view parent_scope_var when pausing at breakpoints in the called function? The variable still exists, right? Just in the parent scope?

Answer 1

Yes, because when you debug to the second breakpoint, python executes the calling function. At this point, python will open the scratch_function.py file.

First breakpoint:

Second breakpoint:

it will only display the variables that exist in the current file, and there is no parent_scope_var variable in the scratch_function.py file, the python interpreter cannot find parent_scope_var , so the watch panel prompts an error: NameError: name 'parent_scope_var ' is not defined .

But as you might guess, the variable still exists at this point, just inside the scratch_script.py file. At this point, you can open the scratch_script.py file, hover the mouse over the parent_scope_var variable, and vscode will clearly show you the variable value at this time.

On a side note, you can also see the previous parent_scope_var variable in the CALL STACK panel.

PS: a setting to display variable values inline in code files when debugging:

//file:settings.json
{
    "debug.inlineValues": "on",  
}