TCL – nested NOT – error

Peter,

Try this:

if { ! ([cequal $hsv “CWP”] && ![cequal $prevloc “”] && [cequal $MSH10 “CHPFXFER”] ) } {

              echo $title “KILL message if Hospital Service…” }

}

Note the parenthesis instead of curly braces.

You don’t need either parenthesis or curly braces here

I would not use cequal

if {$hsv ne “CWP” && $prevloc ne “” && $MSH10 eq “CHPFXFER”} {

             echo $title “KILL message if Hospital Service…” }

}

Since the compare is inside braces you can even pretty it up like:

if {$hsv ne “CWP” &&

       $prevloc ne “” &&

       $MSH10 eq “CHPFXFER”} {

             echo $title “KILL message if Hospital Service…” }

}

Agreed. I’d use the eq and ne operators rather than cequal and you don’t need any grouping. Negating the result of the comparisons just adds confusion to the code.

And, assuming that the the intent of the original code was to negate the result of the three comparisons as a group, it should look like this, I believe.

if { $hsv ne “CWP” && $prevloc eq “” && $MSH10 ne “CHPFXFER” } {

   echo $title “KILL message if Hospital Service…”

}

I’ve never used the eq and ne operators.  Been doing [string equal $a $b] == 1.

Thanks for another Perl of wisdom Charlie!!!

if { ! ($hsv eq “CWP” && $prevloc ne “” && $MSH10 eq “CHPFXFER” ) } {

echo $title “KILL message if Hospital Service…” }

}

Peter

If you want to get rid of the parens, you have to negate the comparisons individually and change the “ands” to “ors”. For example “!(a && !b && c)” is the same as “!a || b || !c”. So, in your case you could write it as:

Terry Kellum wrote

Been doing [string equal $a $b] == 1

Terry, is there an advantage to using the ==1?

There is a caveat when using the string comparison operators eq and ne. Both operands should be surrounded by quotes.

will create a syntax error if hsv is empty because the interpreter evaluates it as

With the quotes

it will evaluate as

Actually, you don’t have to quote the variables, but you do have to quote the string literals.

I understand why it’s better to use the string equal in lieu of cequal, but what advantage does using the “eq” have over the string equal?

Less characters to type, faster execution, more readable. Everything within an “if” condition is already being passed through “expr” automatically, and “eq” is an operator that is interpreted by “expr” without having to call an additional function.

Very close in time of executions.

See: http://wiki.tcl.tk/15322

I use it cause I am lazy!  😀

Less characters to type

However I will say I was told by Jeff Hobbs (Keeper of Tcl) that the string command are *MUCH* more optonized than the old TCLX “C” commands

The timings on the TCLers Wiki page don’t take the “if” condition into account. “if” is automatically calling “expr”, so “if{[string equal]}” is calling one extra command.

Using this pattern, “eq” is about 10% faster.

However, I agree that performance isn’t the main criteria you should use when choosing which one to use.

The primary reason for using string comparisons is that the “==” operator is for numeric comparisons and sometimes evaluates “true” for strings that are not equal.

I use the eq and ne operators because they’re core Tcl operators and they’re easier to read – and are better for us lazy typists ;o)

Back to the original problem…

Now that I re-read the description of the condition…

“…a hospital service of CWP is grounds for rejecting the message unless both the prior patient location is not null and the (Invision) function name is CHPFXFER”

…I think the logic has to look like this:

Testing…