Placeholder argument

It is sometimes useful, with these kinds of rules, to use placeholders that themselves take arguments (see Figure 9.45). This may sound mind-bending at first, but this is as bad as it gets. We re now outside the realm of practical daily application for most software developers. But briefly, in case you re interested, the induction rule can be used to verily statements involving a progression. For example, here s how to prove that all cricket scores are boring. 

If you type the function name in a worksheet cell and then press CONTROL+SHIFT+A, Excel will paste dummy arguments, called placeholder arguments, and add the closing parenthesis. For example, after entering =LINEST, press CONTROL+SHIFT+A. The function will be completed and will appear as follows ... 

The first placeholder argument is selected (highlighted) so that you can enter a value. After entering it, double-click on the next argument to select it. 

You can also type the function name, with or without the opening parenthesis, and then press CONTROL+A or CONTROL+SHIFT+A, as described in Chapter 3. The function placeholder argument will be displayed, highlighted so that you can enter a value or reference (Figure 13-11). 

The name of the array in the procedure must be the name of the placeholder argument of the function. 

A F Insert placeholder arguments and closing parenthesis after typing a function name in a formula Insert placeholder arguments and closing parenthesis after typing a function name in a formula... 

General (i.e., placeholder) arguments in functions or in text are in Geneva italic required arguments are in bold italic L NEST known y s, known x s, const, stats). 

In this example, the prepare function is executed only once. The SQL statement passed to the prepare function contains placeholders to represent values that will be made available once the statement is actually executed. The placeholder is simply a question mark. The arguments to the execute function provide three new values during each execution of the loop. This runs faster than the previous example. 

The abstraction extensions shown in Figure 12 allow GSN elements to be generalised for future instantiation. The uninstantiated entity placeholder denotes that the attached element remains to be instantiated, i.e. at some later stage the abstract entity needs to be replaced with a more concrete instance. The undeveloped entity placeholder denotes that the attached element requires further development, i.e. at some later stage the entity needs to be decomposed and supported by further argument and evidence. 

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