INTRO(9) INTRO(9)
NAME
intro - introduction to Inferno Tk
DESCRIPTION
This section of the manual provides a reference for the
Inferno Tk implementation, which is accessed by Limbo
programs via tk(2), and from sh(1) via sh-tk(1).
The following pages were derived by Vita Nuova from documen-
tation that is
Copyright © 1990 The Regents of the University of Cali-
fornia
Copyright © 1994-1996 Sun Microsystems, Inc.
See copyright(9) for the full copyright notice.
The format of the pages has changed to follow the format of
the rest of this manual, but more important, the content has
been changed (typically in small ways) to reflect the vari-
ant of Tk implemented by Inferno.
Programming Interface
The interface to Inferno Tk is exclusively through the tk(2)
module; all the Tk commands described in this section of the
manual are excecuted by passing them as strings to the cmd
function in that module. The Inferno Tk implementation is
based on the Tk 4.0 documentation, but there are many dif-
ferences, probably the greatest of which is that there is no
associated Tcl implementation, so almost every Inferno
application using Tk will need to have some Limbo code asso-
ciated with it (the sh-tk(1) shell module can also fulful
this rôle). See ``An Overview of Limbo/Tk'' in Volume 2 for
a tutorial-style introduction to the use of Inferno Tk which
summarises the differences from Tk 4.0.
Tk Commands
The command string passed to tk->cmd may contain one or more
Tk commands, separated by semicolons. A semicolon is not a
command separator when it is nested in braces ({}) or brack-
ets ([]) or it is escaped by a backslash (\). Each command
is divided into words: sequences of characters separated by
one or more blanks and tabs.
There is also a `super quote' convention: at any point in
the command string a single quote mark (') means that the
entire rest of the string should be treated as one word.
A word beginning with an opening brace ({) continues until
the balancing closing brace (}) is reached. The outer brace
characters are stripped. A backslash can be used to escape a
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INTRO(9) INTRO(9)
brace in this context. Backslash characters not used to
escape braces are left unchanged.
A word beginning with an opening bracket ([) continues until
the balancing closing bracket (]) is reached. The enclosed
string is then evaluated as if it were a command string, and
the resulting value is used as the contents of the word.
Single commands are executed in order until they are all
done or an error is encountered. By convention, an error is
signaled by a return value starting with an exclamation mark
(!). The return value from tk->cmd is the return value of
the first error-producing command or else the return value
of the final single command.
To execute a single command, the first word is examined. It
must either begin with dot (.) in which case it must name
an existing widget, which will interpret the rest of the
command according to its type, or one of the following
words, each of which is documented in a manual page of that
name in this section:
button entry listbox destroy
menu scale pack image
canvas frame bind update
menubutton scrollbar focus send
checkbutton label grab variable
radiobutton text cursor
Widget Options
Each manual page in this section documents the options that
a particular command will accept. A number of options are
common to several of the widgets and are named as ``standard
options'' near the beginning of the manual page for each
widget. These options are documented in options(9). The
types of value required as arguments to options within
Inferno Tk are documented under types(9).
SEE ALSO
options(9), types(9), tk(2), sh-tk(1), tkcmd(1), wmlib(2),
draw-intro(2), ``An Overview of Limbo/Tk'' in Volume 2.
BUGS
The bracket ([]) command interpretation is not applied con-
sistently throughout the Inferno Tk commands (notably, the
argument to the send(9) command will not interpret this cor-
rectly). Moreover, if the string to be substituted is sig-
nificantly bigger than the command it was substituting, then
it will be truncated.
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