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A.26.  )trace
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User Level Required:  interpreter
 
Command Syntax: 
 
  - )trace
  - )trace )off
 
  - )trace function [options]
  - )trace constructor [options]
  - )trace domainOrPackage [options]
 
where options can be one or more of
 
  - )after S-expression
  - )before S-expression
  - )break after
  - )break before
  - )cond S-expression
  - )count
  - )count n
  - )depth n
  - )local op1 [... opN]
  - )nonquietly
  - )nt
  - )off
  - )only listOfDataToDisplay
  - )ops
  - )ops op1 [... opN ]
  - )restore
  - )stats
  - )stats reset
  - )timer
  - )varbreak
  - )varbreak var1 [... varN ]
  - )vars
  - )vars var1 [... varN ]
  - )within executingFunction
 
Command Description: 
 
This command is used to trace the execution of functions that make up the
FriCAS system, functions defined by users, and functions from the system
library. Almost all options are available for each type of function but
exceptions will be noted below.
 
To list all functions, constructors, domains and packages that are traced,
simply issue
 
)trace
 
To untrace everything that is traced, issue
 
)trace )off
 
When a function is traced, the default system action is to display the
arguments to the function and the return value when the function is exited.
Note that if a function is left via an action such as a THROW, no return
value will be displayed. Also, optimization of tail recursion may decrease
the number of times a function is actually invoked and so may cause less
trace information to be displayed. Other information can be displayed or
collected when a function is traced and this is controlled by the various
options. Most options will be of interest only to FriCAS system developers.
If a domain or package is traced, the default action is to trace all
functions exported.
 
Individual interpreter, lisp or boot functions can be traced by listing their
names after )trace. Any options that are present must follow the functions to
be traced.
 
)trace f
 
traces the function f. To untrace f, issue
 
)trace f )off
 
Note that if a function name contains a special character, it will be
necessary to escape the character with an underscore
 
)trace _/D_,1
 
To trace all domains or packages that are or will be created from a
particular constructor, give the constructor name or abbreviation after
)trace.
 
)trace MATRIX
)trace List Integer
 
The first command traces all domains currently instantiated with Matrix. If
additional domains are instantiated with this constructor (for example, if
you have used Matrix(Integer) and Matrix(Float)), they will be automatically
traced. The second command traces List(Integer). It is possible to trace
individual functions in a domain or package. See the )ops option below.
 
The following are the general options for the )trace command.
 
  )break after
    causes a Lisp break loop to be entered after exiting the traced function.
 
  )break before
    causes a Lisp break loop to be entered before entering the traced
    function.
 
  )break
    is the same as )break before.
 
  )count
    causes the system to keep a count of the number of times the traced
    function is entered. The total can be displayed with )trace )stats and
    cleared with )trace )stats reset.
 
  )count n
    causes information about the traced function to be displayed for the
    first n executions. After the nth execution, the function is untraced.
 
  )depth n
    causes trace information to be shown for only n levels of recursion of
    the traced function. The command
 
    )trace fib )depth 10
 
    will cause the display of only 10 levels of trace information for the
    recursive execution of a user function fib.
 
  )math
    causes the function arguments and return value to be displayed in the
    FriCAS monospace two-dimensional math format.
 
  )nonquietly
    causes the display of additional messages when a function is traced.
 
  )nt
    This suppresses all normal trace information. This option is useful if
    the )count or )timer options are used and you are interested in the
    statistics but not the function calling information.
 
  )off
    causes untracing of all or specific functions. Without an argument, all
    functions, constructors, domains and packages are untraced. Otherwise,
    the given functions and other objects are untraced. To immediately
    retrace the untraced functions, issue )trace )restore.
 
  )only listOfDataToDisplay
    causes only specific trace information to be shown. The items are listed
    by using the following abbreviations:
 
    a        display all arguments
    v        display return value
    1        display first argument
    2        display second argument
    15       display the 15th argument, and so on
 
  )restore
    causes the last untraced functions to be retraced. If additional options
    are present, they are added to those previously in effect.
 
  )stats
    causes the display of statistics collected by the use of the )count and
    )timer options.
 
  )stats reset
    resets to 0 the statistics collected by the use of the )count and )timer
    options.
 
  )timer
    causes the system to keep a count of execution times for the traced
    function. The total can be displayed with )trace )stats and cleared with
    )trace )stats reset.
 
  )varbreak var1 [... varN]
    causes a Lisp break loop to be entered after the assignment to any of the
    listed variables in the traced function.
 
  )vars
    causes the display of the value of any variable after it is assigned in
    the traced function. Note that library code must have been compiled (see
    description of command )compile ) using the )vartrace option in order to
    support this option.
 
  )vars var1 [... varN]
    causes the display of the value of any of the specified variables after
    they are assigned in the traced function. Note that library code must
    have been compiled (see description of command )compile ) using the
    )vartrace option in order to support this option.
 
  )within executingFunction
    causes the display of trace information only if the traced function is
    called when the given executingFunction is running.
 
The following are the options for tracing constructors, domains and packages.
 
  )local [op1 [... opN]]
    causes local functions of the constructor to be traced. Note that to
    untrace an individual local function, you must use the fully qualified
    internal name, using the escape character _ before the semicolon.
 
    )trace FRAC )local
    )trace FRAC_;cancelGcd )off
 
  )ops op1 [... opN]
    By default, all operations from a domain or package are traced when the
    domain or package is traced. This option allows you to specify that only
    particular operations should be traced. The command
 
    )trace Integer )ops min max _+ _-
 
    traces four operations from the domain Integer. Since + and - are special
    characters, it is necessary to escape them with an underscore.
 
Also See: 
o )boot
o )lisp
o )ltrace
 
