Tornado

Tornado 2.0
User’s Guide
Tcl: Calling Target Routines
The shParse utility allows you to embed calls to the C interpreter in Tcl
expressions; the most frequent application is to call a single target routine, with the
arguments specified (and perhaps capture the result). For example, the following
sends a logging message to your VxWorks target console:
tcl> shParse {logMsg("Greetings from Tcl!\n")}
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You can also use shParse to call WindSh commands more conveniently from the
Tcl interpreter, rather than using their wtxtcl building blocks. For example, the
following is a convenient way to spawn a task from Tcl, using the C-interpreter
command sp( ), if you do not remember the underlying wtxtcl command:
tcl> shParse {sp appTaskBegin}
task spawned: id = 25e388, name = u1
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Tcl: Passing Values to Target Routines
Because shParse accepts a single, ordinary Tcl string as its argument, you can pass
values from the Tcl interpreter to C subroutine calls simply by using Tcl facilities to
concatenate the appropriate values into a C expression.
For example, a more realistic way of calling logMsg( )from the Tcl interpreter
would be to pass as its argument the value of a Tcl variable rather than a literal
string. The following example evaluates a Tcl variable tclLog and inserts its value
(with a newline appended) as the logMsg( ) argument:
tcl> shParse "logMsg(\"$tclLog\\n\")"
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5.7.2 Tcl: Calling Under C Control
To dip quickly into Tcl and return immediately to the C interpreter, you can type a
single line of Tcl prefixed with the ? character (rather than using ? by itself to toggle
into Tcl mode). For example:
-> ?set test wonder; puts "This is a $test."
This is a wonder.
->
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