Tornado

Tornado 2.0
User’s Guide
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if then else Statement: In an if command, you may omit the keyword then
before the first command body; but do not omit else if there is a second
command body.
CORRECT: if {$id != 0} {
...
} else {
...
}
INCORRECT: if {$id !=0} then {
...
} {
...
}
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Return Values: Tcl procedures only return strings; whatever meaning the
string has (a list for instance) is up to the application. Therefore each constant
value that a procedure can return must be described in the procedure
documentation, in the RETURNS: block. If a complex element is returned,
provide a complete description of the element layout. Do not use the return
statement to indicate that an abnormal situation has occurred; use the error
statement in that situation.
The following illustrates a complex return value consisting of a description:
# Return a list of 11 items: vxTicks taskId status priority pc
# sp errno timeout entry priNormal name
return [concat [lrange $tiList 0 1] [lrange $tiList 3 end]]
The following illustrates and simple return value:
# This code checks whether the VxMP component is installed:
if [catch "wtxSymFind -name smObjPoolMinusOne" result] {
if {[wtxErrorName $result] == "SYMTBL_SYMBOL_NOT_FOUND"} {
return -1 # VxMP is not installed
} else {
error $result
}
} else {
return 0
# VxMP is installed
}
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Error Conditions: The Tcl error command raises an error condition that can be
trapped by the catch command. If not caught, an error condition terminates
script execution. For example:
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