Topic: monitored variable

topics > computer science > programming > Group: debugging

parallel processing
process control

alarm reporting
aspect-oriented programming
execution tracing
help in UserInterface
immediate computation
logging data and events
monitored statements and events
software maintenance by patching
variable as function that accesses an object's value


Variables may be monitored whenever they are assigned or accessed. This is useful in debugging and program statistics. If the variable is a parameter, monitors can provide type checking, data conversions, and parameter passing modes. Monitored variable access may be provided automatically or the monitoring procedure may be initiated by the user. Monitors may indicate important events or initiate breakpoints. Using a monitor is using an accessing function instead of direct variable reference. (cbb 5/80)

A 'filter' filters values sent to or from a variable. (cbb 12/92)

Subtopic: monitor variables during execution up

Quote: selected variables can be monitored during execution; most-recently-updated variables appear on the screen [»teitT6_1981]
Quote: instead of signaling events can automatically display information, e.g., the current state of a screen editor [»drapSW_1986]
Quote: monitor selected variables during execution of the program [»teitT6_1979]
Quote: ALADDIN breakpoints occur on error conditions specified via logical relations between components [»fairRE7_1979]
Quote: associated variables are especially applicable to program debugging [»hansDR3_1978]
Quote: PROMOD has an LED that is on whenever a contact is closed; for visual check; also test probe and contact forcing pins [»instrumentcontrol]
Quote: hooks can be attached to variables; when variable changes, its hook is run; e.g., to update related data structures [»stalRM6_1981]

Subtopic: describe variable on selection up

Quote: in Magpie, whenever an item is selected, descriptive information is displayed in an adjoining pane [»deliNM5_1984]

Subtopic: patching assignments up

Quote: use C's comma operator to syntactically add code to assignments while preserving C semantics

Subtopic: tracked value up

Quote: track the origin of nulls by piggybacking an id; may help with diagnosis in one third of cases [»bondMD10_2007a]

Subtopic: examples up

Quote: in Snobol4, the value of an associated variable is replaced by a trapping block containing the real value, process description, etc. [»hansDR3_1978]
Quote: in SL5, a transmitter is a procedure associated with a parameter that intercepts actual arguments and returns a value [»hansDR5_1978]
QuoteRef: hansDR5_1978 ;;397 "A [argument] transmitter may be a built-in procedure, a programmer-defined procedure, or an environment.
QuoteRef: simscrip_1971 ;;31 Monitored variables-- routine executed whenever accessed (left or right hand side or both)
QuoteRef: simscrip_1971 ;;150 Move from .. and move to .. for accessing a monitored variable
QuoteRef: wegbB5_1974 ;;34 Sensitive mode (mode, predicate, action) tested whenever variable assigned i.e. predicate: action
QuoteRef: ziegEW4_1974 ;;131 procedure may be associated with an element and the location of an element can be saved.
Quote: Videospec displays process loops as graphical representations of conventional controllers; include engineering units, tags, set points, alarms, auto/manual [»controleng]
Quote: a process control operator monitors for rare events; display for pattern recognition, e.g. circular spokes if all ok [»dallR1_1982]
QuoteRef: instrumentcontrol ;;2/79 45 Crutchley W: Loop status displays are the most common: show loop name, identifier, setpoint, measured value, units of measurement alarm status, auto/manual/remote status.
QuoteRef: polsPG_1972 ;;562 When testing for state change, searched list for true condition each time an interrupt comes in
Quote: a 'filter' in SL5 is a procedure that filters values assigned to a variable or fetched from a variable [»hansDR5_1978a]
QuoteRef: seedH_1971 ;;156 level control indicators which turned on when field changes or higher level indicator goes on.
Quote: the EDSAC accumulator was attached to a loudspeaker; users could detect small changes in rhythm [»campM1_1980]

Subtopic: monitoring vs. dump up

Quote: Wilkes preferred print orders and post-mortem routines over "peeping", i.e., observing a program's progress through a CRT monitor [»wilkMV_1951]
Quote: EDSAC programmers could view one bank of 32 words while the program was running; called "peeping" [»campM1_1980]

Subtopic: data breakpoints up

Quote: data breakpoints in dbx cost 85,000x due to context switches and trap costs [»wahbR6_1993]
Quote: implement data breakpoints by code patching; 42% overhead; use segmented bitmap, reserved registers, loop entry checks, range checks

Related Topics up

Group: parallel processing   (41 topics, 1125 quotes)
Group: process control   (13 topics, 106 quotes)

Topic: alarm reporting (4 items)
Topic: aspect-oriented programming (2 items)
Topic: debugger (37 items)
Topic: execution tracing (42 items)
Topic: help in UserInterface (33 items)
Topic: immediate computation (8 items)
Topic: logging data and events (17 items)
Topic: monitored statements and events (16 items)
Topic: software maintenance by patching (27 items)
Topic: variable as function that accesses an object's value
(21 items)

Updated barberCB 9/04
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Thesa is a trademark of C. Bradford Barber.