11. Special Variables

Logo takes special action if any of the following variable names exists. They follow the normal scoping rules, so a procedure can locally set one of them to limit the scope of its effect. Initially, no variables exist except for ALLOWGETSET, CASEIGNOREDP, and UNBURYONEDIT, which are TRUE and buried.

allowgetset
caseignoredp
erract
fullprintp
loadnoisily
printdepthlimit
printwidthlimit
redefp
startup
unburyonedit
usealternatenames

allowgetset

ALLOWGETSET (variable)

if TRUE, indicates that an attempt to use a procedure that doesn't exist should be taken as an implicit getter or setter procedure (setter if the first three letters of the name are SET) for a variable of the same name (without the SET if appropriate).

caseignoredp

CASEIGNOREDP (variable)

if TRUE, indicates that lower case and upper case letters should be considered equal by EQUALP, BEFOREP, MEMBERP, etc. Logo initially makes this variable TRUE, and buries it.

See section equalp , beforep , memberp .

erract

ERRACT (variable)

an instructionlist that will be run in the event of an error. Typically has the value [PAUSE] to allow interactive debugging.

See section pause .

fullprintp

FULLPRINTP

if TRUE, then words that were created using backslash or vertical bar (to include characters that would otherwise not be treated as part of a word) are printed with the backslashes or vertical bars shown, so that the printed result could be re-read by Logo to produce the same value. If FULLPRINTP is TRUE then the empty word (however it was created) prints as ||. (Otherwise it prints as nothing at all.)

loadnoisily

LOADNOISILY (variable)

if TRUE, prints the names of procedures defined when loading from a file (including the temporary file made by EDIT).

See section edit .

printdepthlimit

PRINTDEPTHLIMIT (variable)

if a nonnegative integer, indicates the maximum depth of sublist structure that will be printed by PRINT, etc.

See section print .

printwidthlimit

PRINTWIDTHLIMIT (variable)

if a nonnegative integer, indicates the maximum number of members in any one list that will be printed by PRINT, etc.

See section print .

redefp

REDEFP (variable)

if TRUE, allows primitives to be erased (ERASE) or redefined (COPYDEF).

See section erase , copydef .

startup

STARTUP (variable)

if assigned a list value in a file loaded by LOAD, that value is run as an instructionlist after the loading.

See section load .

unburyonedit

UNBURYONEDIT (variable)

if TRUE, causes any procedure defined during EDIT or LOAD to be unburied, so that it will be saved by a later SAVE. Files that want to define and bury procedures must do it in that order.

See section edit , See section load , See section save .

usealternatenames

USEALTERNATENAMES (variable)

if TRUE, causes Logo to generate non-English words (from the Messages file) instead of TRUE, FALSE, END, etc.