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## 16.26 )trace

ugSysCmdtrace

trace

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 Axiom 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 Axiom 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 Common Lisp break loop to be entered after exiting the traced function.
)break before
  causes a Common 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 n-th 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 Axiom 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 Common 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 ugSysCmdcompile ) 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 ugSysCmdcompile ) 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: )boot ugSysCmdboot, )lisp ugSysCmdlisp, and )ltrace ugSysCmdltrace.

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