Tornado

B
Tcl
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expr and Control Flow Commands: Do not use expr in commands such as if,
for or while except to convert a variable from one format to another:
CORRECT: if {$id != 0} {
CORRECT: if {[expr $id] != 0} {
INCORRECT: if {[expr $id != 0]} {
expr and incr: Do not use expr to increment or decrement the value of a
variable. Use incr instead.
B
CORRECT:
incr index
CORRECT: incr index -4
INCORRECT: set index [expr $index + 1]
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wtxPath and wtxHostType: Use these routines when developing tools for
Tornado. With no arguments, wtxPath returns the value of the environment
variable WIND_BASE with a “/” appended. With an argument list, the result of
wtxPath is an absolute path rooted in WIND_BASE with each argument as a
directory segment. Use this command in Tornado tools to read resource files.
The wtxHostType call returns the host-type string for the current process (the
environment variable WIND_HOST_TYPE. if properly set, has the same value).
For example:
source [wtxPath host resource tcl]wtxcore.tcl
set backenddir [wtxPath host [wtxHostType] lib backend]*
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catch Command: The catch command is very useful to intercept errors raised
by underlying procedures so that a script does not abort prematurely.
However, use the catch command with caution. It can obscure the real source
of a problem, thus causing errors that are particularly hard to diagnose. In
particular, do not use catch to capture the return value of a command without
testing it. Note also that if the intercepted error cannot be handled, the error
must be resubmitted exactly as it was received (or translated to one of the
defined errors in the current procedure):
CORRECT: if [catch "dataFetch $list" result] {
if {$result == "known problem"} {
specialCaseHandle
} else {
error $result
}
INCORRECT:
catch "dataFetch $list" result
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