import's recursion

[Duncan Booth]

mailspamforme at yahoo.com (_rui_) wrote in 
news:2d9b77f4.0212052022.405d2813 at posting.google.com:

> hi, list!
> Tell me please, why recursion is absent?
> 
> 
> foo.py
> ~~~~~~
> import foo
> 

This is what happens:

You run the script foo.py, this creates a module called '__main__',
compiles the code into it, executes the code.

The code in module __main__ executes 'import foo':
   Looks in sys.modules for a module called foo.
   There isn't one so:
      Finds foo.py
      Compiles foo.py into foo.pyc
      Creates a new module 'foo' containing the foo code.
      Stores a reference to module foo in sys.modules
      Starts to execute module 'foo'.
      The code in module foo executes 'import foo':
         Looks in sys.modules for a module called foo.
         Finds one and returns it:
            Sets the variable foo.foo to module foo
      Module foo has finished executing.
   __main__.foo is set to module foo

In short imports aren't recursive because attempting to import a module 
that is partly imported gives you a reference to the module but doesn't 
attempt to reexecute the code it contains. This means you may get a 
reference to a module that doesn't yet contain any functions or classes, 
but that isn't a problem so long as you dont attempt to reference them 
until later when all the imports have completed.

-- 
Duncan Booth                                             duncan at rcp.co.uk
int month(char *p){return(124864/((p[0]+p[1]-p[2]&0x1f)+1)%12)["\5\x8\3"
"\6\7\xb\1\x9\xa\2\0\4"];} // Who said my code was obscure?