14.10. Evaluate
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## 14.10. Evaluate

The Evaluate panel is an inline Lua REPL against the paused state. The top half is an input editor; the bottom half is a read-only log of previous expressions and their results.

- Enter Lua code and press `Ctrl+Return` (or click Evaluate) to run it against the paused state. The evaluator runs the code in a protected way, so runtime errors are caught and reported in the output rather than terminating Wireshark.
- No `=` or `return` is needed — bare expressions auto-return their value, the same way Watch rows do (see Section 14.6, “Watch”). The legacy `=expr` prefix from older Lua REPLs is still tolerated, just redundant.
- Clear empties both the input and the output.

The panel is enabled only while the debugger is paused. Typical uses:

- Inspect a value — `pinfo.src`, `tostring(pinfo.dst)`, or `sessions[pinfo.number]`.
- Mutate state — `_G.my_flag = true`, `my_table.field = 99`. (For read-only observation prefer the Watch panel; expression watches re-evaluate automatically on every pause without taking up the Evaluate output history.)
- Run a one-off statement — set a global, push a row into a table, or call a logging helper.

Scope. The evaluator runs against the paused state with the same custom `_ENV` as expression watches; bare identifiers resolve against locals, then upvalues, then globals (see Section 14.5, “Variables”). So `pinfo.src` works the same way `Locals.pinfo.src` works, and library names like `string` and `tostring` fall through to globals automatically.

Limitations.

- Locals cannot be mutated by assignment. A statement like `foo = 42` writes to `_G.foo`, not to a local `foo`. Use `debug.setlocal()` if you really need to mutate a local.
- Mutating globals is destructive. Changes persist after Continue and will affect subsequent dissection.
- Long-running expressions are aborted (Lua 5.4+). The evaluator caps execution time so a runaway `while true do end` cannot hang the GUI. On Lua 5.3 builds the cap is inactive; see the Expression watches section for details.

After an evaluation the Stack Trace, Variables, and Watch panels are refreshed because the expression may have mutated state the other panels display.

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