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-*- mode: outline -*-
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* How debug?
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When your InitFile has a bug, or when you load external files that cause
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errors, the bug is often hard to find, because the Emacs Lisp reader does not
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know about line numbers and files – it just knows an error happened, and
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that’s it.
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You have several options:
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* Binary Search – select half of the file in a region, and M-x eval-region.
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Depending on whether that causes the error or not, split this half or the
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other half again, and repeat.
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* Simplified Binary Search – add (error “No error until here”) in the
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middle of your file. If you get the error “No error until here” when
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reloading the file, move the expression towards the back of the file,
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otherwise towards the front of the file.
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* Use a keyboard macro that moves forward one expression (sexp) and
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evaluates it.
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* Try the CommandLine? switch --debug-init.
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* Shouldn’t (setq debug-on-error t) help?
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* Using edebug.
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The main entry point is ‘M-x edebug-defun’ (also on ‘C-u C-M-x’). Use it
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instead of `C-x C-e’ or ‘C-M-x’ to evaluate a ‘defun’ and instrument it for
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debugging.
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You can disable edebug on a function by evaluating the function again using
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‘C-M-x’.
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