The PREFS object contains a list of system-wide properties that control the look and feel of Logo. If you SAVE your workspace, the current settings are stored in the saved file. If you load a workspace that has been saved before, the settings are restored.
Contains the name of your Logo app.
APPNAME contains the name of your Logo app if Logo runs in app mode. If Logo does not run in app mode, APPNAME outputs an empty word.
GPROP “PREFS “APPNAME Result:
Controls the lowest array or grid index.
The ARRAYBASE property controls the lowest value that you can use as an array or grid index. You may want to set the value to 1 if you prefer to index arrays and grids with a starting value of 1; actually, any starting value is legal as long as you are comfortable with that value.
GPROP “PREFS “ARRAYBASE Result: 0
Controls the amount of data that Logo saves and restores automatically.
Logo can be configured to save your workspace, your turtles and everything else in frequent intervals. The AUTOSAVE property can be set to one of four values to tell Logo what to save:
OFF: Nothing will be saved.
WORKSPACE: Logo saves all procedures, names and property lists. This is the default.
TURTLES: As with
WORKSPACE, plus all turtles and the contents of the Graphics panel.
ALL: As with
TURTLES, plus the Listener, all controls and bitmaps, and all global built-in names.
In the Web version, you can also set the AUTOSAVE property with an addition of an “autosave” argument to the link, as in this example:
This is especially handy for classroom computers where you have a link for students to click.
If Logo is running a Logo app, the setting of this property is ignored. A Logo app never saves any autosave data.
GPROP “PREFS “AUTOSAVE Result: WORKSPACE
Controls the conversion of input to upper case.
CASE controls the way quoted words are converted to upper case. If
CASE is TRUE, which is the default, Logo converts lowercase quoted
words to upper case as they are input to Logo. If
CASE is set to
FALSE, the case of quoted words is not changed.
Note that quoted words enclosed in vertical bars, or back-quoted words are not affected.
GPROP “PREFS “CASE Result: TRUE
Displays turtles with their pen color.
Setting the COLORED.TURTLES property to TRUE causes turtles to draw themselves using the current pen color if it is anything else but black.
SETPC “RED ; turtle 0 displays in red
Controls the use of the Logo debugger.
THe DEBUGGER property controls whether the Logo debugger should be activated in case of a runtime error. If this property is set to TRUE (which is the default), the debugger activates so you can debug the problem. If set to FALSE, Logo prints the runtime error along with a stack trace and returns to topllevel.
Controls the Listener font.
The FONT property gets or sets the font that the Listener panel uses for output. For the font format, please see the SETFONT command.
GPROP “PREFS “FONT Result: [MONOSPACE 12 0]
Controls the font used when creating a control.
The CONTROLS.FONT property gets or sets the font that Logo uses when creating a control. Set this property before creating a control so Logo can pick it up. For the font format, please see the SETFONT command.
GPROP “PREFS “CONTROLS.FONT Result: [HELVETICA 12 0]
Controls the font used when creating a control.
The TURTLE.FONT property gets or sets the font that turtles use when drawing text. For the font format, please see the SETFONT command.
GPROP “PREFS “TURTLE.FONT Result: [HELVETICA 12 0]
Controls the maximum number of lines in the Listener panel.
LISTENER.LINES controls the number of lines that the Listener panel’s output field will display. If Logo displays more than the given value, the oldest lines will be lost.
GPROP “PREFS “LISTENER.LINES Result: 100
Controls whether all output in the Listener panel is readonly.
LISTENER.READONLY controls whether all output in the Listener panel is read only or not. If output is read only, it cannot be erased; only user input can be edited or erased. Since this is a good setting for students, the property is set to TRUE for all classroom logins with a student password.
GPROP “PREFS “LISTENER.READONLY Result: TRUE
Alters Logo’s language.
This property contains the current language that Logo uses to talk to
you as a three or five-letter ISO code. The actual setting depends on
your browser and system settings. For U.S. computers, the value is, for
EN. Logo speaks a few different languages; you can see if
Logo speaks a specific language by setting the appropriate language
code. If Logo does not speak that language, it falls back to U.S.
Please note that currently only messages are changed. We are working on providing translations for all of Logo including dialogs, menus, and more.
GPROP “PREFS “LOCALE Result: EN
Controls the file extension used for images if none was supplied.
This is the default file extension for graphics images. Logo uses this extension if you access an image file without a specific extension.
GPROP “PREFS “PICTURE.FORMAT Result: PNG
Controls the number of decimals that Logo prints.
PRECISION controls the number of decimal points that Logo outputs when printing a number. The value can be anything between 0 and 15; the value -1 instructs Logo to always print an appropriate number of decimals depending on the value.
GPROP “PREFS “PRECISION Result: 2
Controls the printing of bitmaps and turtles.
PRINT.BITMAPS controls whether the the saving or printing of the Graphics panel includes all visible bitmaps and turtles. If set to TRUE (which is the default), all visible bitmaps and turtles are saved or printed as well. Setting this property also changes the setting of the checkbox in the Save Picture and Print Picture dialogs.
GPROP “PREFS “PRINT.BITMAPS Result: TRUE
Relaxes the syntax requirements of Logo.
If set to TRUE, you do not need to use the colon to read the value of a
name (as in
:VALUE). Logo first checks if a name is a procedure; if
RELAXED.SYNTAX is set to true, Logo checks if a name has a
GPROP “PREFS “RELAXED.SYNTAX Result: FALSE
Controls the maximum number of nested procedure calls.
STACKSIZE controls the maximum number of nested procedure calls. If an executing Logo program calls more than this number of nested procedures, the program terminates with a runtime error.
GPROP “PREFS “STACKSIZE Result: 1000
Controls the tab stop size used in the Listener’s output field.
TAB controls the tab stop size used in the Listener’s output field. This is the approximate number of spaces that Logo would use when printing the Tab character (which is CHAR 9); see also the PRINT command for a list of special printing characters.
GPROP “PREFS “TAB Result: 4
Reports the user’s name.
This is the name that your Logo licenses is registered under; if you use the trial version of Logo, the user name is “Guest User”.
GPROP “PREFS “USERNAME Result: Guest User
This variable contains a property list of global program and system settings. All of its properties are read-only.
Reports the browser name.
BROWSER contains the name of the browser that Logo is executing in. For
the desktop version, BROWSER reports the word
GPROP “LOGO.ENV “BROWSER Result: CHROME
Reports the device that Logo is executing upon.
ENVIRONMENT contains a word describing the browser environment;
currently one of
GPROP “LOGO.ENV “ENVIRONMENT Result: DESKTOP
Controls whether to have Terrapin Logo occupy the entire screen or display in normal size.
FULLSCREEN sets Terrapin Logo to fullscreen if its value is set to TRUE, or to normal size if its value is set to FALSE. It reports the current fullscreen setting.
Not all browsers allow a program to occupy the entire screen. In that case, setting the FULLSCREEN property to TRUE does not have any effect.
Also, do not expect any Logo panel to properly report its size immediately after setting the property. The change to fullscreen and back is independent from the execution of a Logo program, and resizing all panels takes some time before Logo is made aware of the changes.
GPROP “LOGO.ENV “FULLSCREEN Result: FALSE
Reports the size of the browser window (Web) or the desktop (Desktop version).
SCREENSIZE reports the size of the browser window (Web) or the desktop (Desktop version) in pixels.
GPROP “LOGO.ENV “SCREENSIZE Result: [1400 700]
Reports the Logo version number.
VERSION reports the Logo version number as a numeric value.
GPROP “LOGO.ENV “VERSION Result: 5