IBM Switch 15 Manual de usuario descargar pdf (Pagina 119)

109

Building CLEM Expressions

Complex Expressions

Express ions can also be lengthy and more complex. The following expression returns true if the

value of two ﬁelds ($KX-Kohonen and $KY-Kohonen) fall within the speciﬁed ranges. Notice that

here the ﬁeld names are single- quoted bec ause the ﬁeld names contain s pe cial char acters.

('$KX-Kohonen' >= -0.2635771036148072 and '$KX-Kohonen' <= 0.3146203637123107

and '$KY-Kohonen' >= -0.18975617885589602 and

'$KY-Kohonen' <= 0.17674794197082522) -> T

Several function s, such as string functions, requ ire you to enter several param eters using correct

syntax. In the following example, the function subscrs is used to retu r n the ﬁrst character of a

produce_ID ﬁeld, indicating whether an item is organic, genetic ally modiﬁed, or conventional.

The r esults of an expression are described by -> `result`.

subscrs(1,produce_ID) -> `c`

Similarl y, the following expres sion is:

stripchar(`3`,`123`) -> `12`

It is importa nt to note that characters are always encapsulated within s ingle backquotes.

Combining Functions in an Expression

Frequently, CLEM expressions consi st of a combination of functions. The following fun ction

combines subscr and lowertoupper to return the ﬁrst character of produce_ID and co nvert it to

upper case.

lowertoupper(subscr(1,produce_ID)) -> `C`

This same expression can be writte n in shorthand as:

lowertoupper(produce_ID(1)) -> `C`

Another commonly used combina tion of functions is:

locchar_back(`n`, (length(web_page)), web_page)

This expression locate s the character `n` withi n the values of the ﬁeld web_page reading backward

from the last character of the ﬁeld value. By includ ing the length f unction as well, the expression

dynamically calculates the length of the current value rather than using a static num ber, such a s 7,

which will be inva lid for values with less than seven characters.

Special Functions

Numerous special functions (preceded with an @ symbol) are available. Commonly used

functions include:

@BLANK('referrer ID') -> T

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IBM Switch 15 Manual de usuario Pagina 119