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dynamic scope from frame, static scope from ???


Hello,

(had an interesting hallway conversation)

The languages that GDB debugs, being good old fashoned procedural, have both a static (compile time) and dynamic (run time) [scope] information. Static information includes things like the current language, source line, and the names of variables that are in scope. The dynamic information includes things like the call chain and the actual location (instance) of a variable.

Given a live process (or core file), the frame provides access to the dynamic info, and via the frame's PC, the static information.

Conversely, when there is no program. GDB has the current source-and-line and that can be used to determine static program information. For instance, the break command refers to static information when setting a breakpoint.

GDB's slowly pushing the frame through to the procedures that need access to the dynamic information. However, I don't know that we've addressed the case where a process needs access to the static information? Should there be dogma (similar to "there is always a frame") that covers the static case?

Off hand I can think of several ways of doing this:

- create a static-frame (it has no dynamic state) and use that
- pass the source-and-line or block where needed
functions would get both sal and a possibly null frame
- pass some new structure that includes other info such as the selected language (if its different to what it should be)?


thoughts?
Andrew


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