dissector
Note: This is taken from the Chicken Wiki, where a more recent version could be available.
An object inspector for Chicken.
Taylor Campbell
Send questions, comments, bugs, et cetera to Taylor Campbell, either via email at campbell (at) mumble (dot) net or via IRC in #scheme or in #chicken on Freenode (irc.freenode.net).
The dissector is an interactive object structure inspector. It allows for expedient inspection of a tree of objects' components. It consists of a current 'focus object' — the object currently being dissected — a menu of that object's components, and an interactive command reader for commands that the user uses to interactively browse the objects.
<procedure>(dissect object [inport [outport]])</procedure>
Dissect invokes the dissector. If given, inport & outport specify the ports to & from which commands & output are read & written.
Dissector commands are put each on single lines. The first part of the line should be a symbol. The remainder of the line consists of arguments to the command. After certain commands, a summary of the focus object may be printed. This summary is truncated to fit within your terminal. (Actually, it's truncated to fit within 72 lines. But that's usually enough for most terminals. And this doesn't necessarily apply if using a custom printer.) Other commands may print a selection from the menu of an object's components. In this selection is printed summaries of a number of an object's components. Each component is given a particular index; this index may be used to select the respective subcomponent of the focus object. A list of dissector commands and help for them can be acquired with the help command, or the ? alias for it.
There are several parameter objects that affect the dissector's operation.
<parameter>dissection-prompt</parameter>
This specifies the prompt to be printed before waiting for the user to send a command. Must be a string.
<parameter>dissection-menu-section-size → exact, positive integer</parameter>
This specifies the maximum number of entries to be printed when disclosing a section of a menu to the user. Must be an exact, positive integer.
<parameter>dissection-overview-printer</parameter>
The function to print a dissection's overview. The function takes two arguments: the object to print and the port to print it to. Must be a procedure.
<parameter>dissection-menu-entry-printer</procedure>
The function to print a dissected object's components. It takes three arguments: the object to print, the number of characters already printed to the port on the current line, and the port to print the object to. Must be a procedure.
<parameter>dissection-right-margin</parameter>
The right margin for printing objects. This is merely a hint to the dissection-...-printer parameters. Its default is 71, to fit nearly all terminals. Must be an exact, positive integer.
apply expression
alias: a
Evaluates expression in the interaction environment, which should produce a unary function, and applies it to the current focus object. This does not modify the current dissection.
apply/dissect expression
alias: ad
Evaluates expression in the interaction environment, which should produce a unary function, and applies it to the current focus object. It must return at least one value. If it returns one value, that value is dissected; if it returns more than one, a list containing the values is dissected.
dissect expression
alias: d
Evaluates expression in the interaction environment and dissects the value that is produced. Expression may evaluate to one or more values. With one value, that value is dissected; with more, a list of the values is dissected.
eval expression
aliases: e scheme
Evalutes expression in the interaction environment and prints the results. This does not modify the current dissection.
help [command]
alias: ?
If command is absent, prints out a brief help synopsis for every supported command; otherwise prints out help for command.
history
alias: h
Prints the dissection history.
menu
alias: m
Prints just the current menu.
overview
alias: o
Prints the focus value, without a menu.
alias: p
Prints out the entirety of the current dissection.
quit
aliases: q exit
Quits the dissector.
select index [deep-index ...]
alias: s
Selects the indexth slot in the focus object to dissect next. Index must be a valid index into the focus object, as shown by the menu. If more than one index is passed, it is as if the select command were applied multiple times, to each successive index.
up [count]
alias: u
Moves count elements back up the history of dissected objects. If count is absent, it defaults to 1.
walk [slot-count]
alias: w
Moves the current menu selection by slot-count elements. If slot-count is negative, the menu is moved backwards; if it's positive, it is moved forwards. If it is absent, the menu is moved forward by (dissection-menu-section-size) slots.
Copyright (C) 2004, Taylor Campbell
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