Marko Rauhamaa wrote: > Veek M <vek.m1...@gmail.com>: > >> https://en.wikipedia.org/wiki/Call_stack >> >> 'Programming languages that support nested subroutines also have a >> field in the call frame that points to the stack frame of the latest >> activation of the procedure that most closely encapsulates the >> callee, i.e. the immediate scope of the callee. This is called an >> access link or static link (as it keeps track of static nesting >> during dynamic and recursive calls) and provides the routine (as well >> as any other routines it may invoke) access to the local data of its >> encapsulating routines at every nesting level. >> >> Some architectures, compilers, or optimization cases store one link >> for each enclosing level (not just the immediately enclosing), so >> that deeply nested routines that access shallow data do not have to >> traverse several links; this strategy is often called a "display".' >> >> 1. What is the difference between a 'call frame' and a 'stack frame' >> in the above context? > > There's no difference. > >> 2. He's saying that within the 'call frame' (whatever that is) >> there's an address to one of the previous stack frames of the wrapper >> function ? What does all that mean in terms of nested functions? >> Access link? How are nested function stacks setup.. > > The classic C stack frame contains two addresses (in addition to the > arguments and local variables): > > * the return address in the calling function > > * the frame pointer in the calling function > > Some languages (notably Pascal) add a third address: > > * the frame pointer in the outer function > > Often, the outer function is the same as the calling function. > However, if the inner functions call each other, the outer function > may be further up the stack. Since the outer function's local > variables are seen by the inner functions, the extra pointer is needed > to access them directly. > > Python has nested functions. Thus, the same technique can be used to > implement Python's internal call stack. > >> 3. What exactly is a traceback object > > It is an object that reports details of the call stack. It is mostly > useful for troubleshooting. > >> How exactly does an exception fit in with tracebacks? How does all >> this fit in with nested functions? > > Well, the traceback object contains also the exception since it is > essential for troubleshooting. > >> 4. When you call a nested function (decorator), it generally returns >> a wrapper function but I thought he was just returning a reference to >> a function object but obviously since it can see it's environment, >> how is the stack being setup? > > Now I don't exactly understand your question. > > > Marko
Umm.. here's an article on windows exception handling.. i was hoping for something like that.. (it's very badly written but informative about win32 exception handling - i'm still reading it) wanted something similar.. I'll quote the highlights.. I KNOW NOTHING about ANY exception handling so.. http://www.codeproject.com/KB/cpp/exceptionhandler.aspx ' On the Intel Win32 platform, the FS register always points to the current TIB. Thus, at FS:[0] you can find a pointer to an EXCEPTION_REGISTRATION structure. Now I'm getting somewhere! When an exception occurs, the system looks at the TIB of the faulting thread and retrieves a pointer to an EXCEPTION_REGISTRATION structure. In this structure is a pointer to an _except_handler callback function. The operating system now knows enough to call the _except_handler function,' 'When you use a compiler's _try/_except syntax, the compiler also builds the EXCEPTION_REGISTRATION struct on the stack. I'm simply showing you a simplified version of what a compiler would do if you used _try/_except.' -- https://mail.python.org/mailman/listinfo/python-list
