Issue accessing global variables

Hi all. The code below demonstrates a bug in accessing global variables. As of 29-Sep-2017, this bug is produced when run with this brython version: https://cdn.rawgit.com/brython-dev/brython/stable/www/src/brython.js But it is not produced with this brython version: https://cdnjs.cloudflare.com/ajax/libs/brython/3.3.20/brython.js

It should print 42 all 4 times, but in the buggy version, the first (straightforward) case fails, claiming the global variable is not defined:

`

def setSomeGlobal():
    global someGlobal
    someGlobal = 42

setSomeGlobal()

def getSomeGlobal():
    return someGlobal

# Directly accessing the global will fail:

try: print('someGlobal -->', someGlobal)  # Error: name 'someGlobal' is not defined
except Exception as e: print('Error:', e)

# But "indirectly" accessing the global succeeds:

print('globals()["someGlobal"] --> ', globals()["someGlobal"]) # 42 (ok)
print('getSomeGlobal() --> ', getSomeGlobal())                 # 42 (ok)
print('(lambda:someGlobal)() --> ', (lambda:someGlobal)())     # 42 (ok)`

Thanks!

David

[PierreQuentel]

Like in CPython, the scripts are run each in its own namespace ; sharing the same namespace for all scripts would cause terrible bugs.

To share variables between scripts you can use the object browser.window :

<script type="text/python">
from browser import alert, window

def function_a():
  alert("function a")

def function_b():
  function_a()
  alert("function b")

window.function_b = function_b
</script>

<script type="text/python">
from browser import window

window.function_b()
</script>

[darthglowball]

I can’t acces global functions from one script in other scripts. I have two scripts in the main html body:

<script type="text/python">
  from browser import alert

  def function_a():
      alert("function a")
  
  global function_b
  def function_b():
      function_a()
      alert("function b")
      
</script>
<script type="text/python">
  function_b()
</script>

In Chrome the error is: Traceback (most recent call last): NameError: name 'function_b' is not defined brython.js:5028 Uncaught Error at Object._b_.NameError.$factory (eval at $make_exc (brython.js:7382), <anonymous>:101:327) at Object.$B.$global_search (brython.js:5690) at eval (eval at $B.loop (brython.js:5012), <anonymous>:11:17) at $B.loop (brython.js:5012) at $B.loop (brython.js:5017) at $B.inImported (brython.js:5002) at $B.loop (brython.js:5018) at IDBOpenDBRequest.idb_cx.onsuccess (brython.js:4982)

The globals are not found in the second script’s globals(). They aren’t in browser.window either (would that be a good place for Python globals?) A workaround is by putting your globals in __BRYTHON__ (I haven’t had any name clashes with internal Brython variables, so it seems safe?). Still really annoying though to do it like that.