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If an expression in your program produces a value containing circular list structure, you may get an error when Edebug attempts to print it.
One way to cope with circular structure is to set print-length
or print-level to truncate the printing. Edebug does this for
you; it binds print-length and print-level to the values
of the variables edebug-print-length and
edebug-print-level (so long as they have non-nil
values). See Output Variables.
If non-
nil, Edebug bindsprint-lengthto this value while printing results. The default value is50.
If non-
nil, Edebug bindsprint-levelto this value while printing results. The default value is50.
You can also print circular structures and structures that share
elements more informatively by binding print-circle
to a non-nil value.
Here is an example of code that creates a circular structure:
(setq a '(x y))
(setcar a a)
Custom printing prints this as ‘Result: #1=(#1# y)’. The ‘#1=’ notation labels the structure that follows it with the label ‘1’, and the ‘#1#’ notation references the previously labeled structure. This notation is used for any shared elements of lists or vectors.
If non-
nil, Edebug bindsprint-circleto this value while printing results. The default value ist.
Other programs can also use custom printing; see cust-print.el for details.