| |
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| | can understand the logical structure of the conditions. It's also a |
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| | good idea to put comments throughout such conditional blocks so it's |
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| | clear what is going on. |
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| | |
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| | .SS Existential Conditionals |
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| | |
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| | |
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| | .SS Comparison Conditionals |
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| | .SS Existential Conditional Directives |
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| | |
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| | There are three Existential Conditionals: \'.ifall\', \'.ifany\', and \'.ifnone\'. |
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| | Each has the same syntax: |
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| | |
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| | .nf |
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| | ExistentialDirective [var] ... |
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| | included if True |
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| | |
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| | .else # optional |
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| | include if False |
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| | |
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| | .fi |
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| | .fi |
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| | |
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| | In other words, existential conditionals require |
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| | .B one or more variable references. |
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| | In each case, the actual content of that variable is ignored. The test is merely |
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| | checking to see |
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| | .B if a variable by that name exists. |
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| | Nothing else may appear on an existential conditional line, except, |
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| | perhaps, a comment. |
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| | |
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| | The three forms of existential conditional tests implement three different kinds of |
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| | logic: |
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| | |
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| | .nf |
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| | .ifall [var1] [var2] ... |
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| | |
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| | This is a logical "AND" operation. ALL of the variables, \'var1\', \'var2\' ... |
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| | must exist for this test to be True. |
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| | |
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| | .ifany [var1] [var2] ... |
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| | |
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| | This is a logical "OR" operation. It is True of ANY of the variables, |
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| | \'var1\', \'var2\' ... exist. |
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| | |
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| | .ifall [var1] [var2] ... |
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| | |
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| | This is a logical "NOR" operation. It is True only if NONE of the variables, |
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| | \'var1\', \'var2\' ... exist. |
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| | .fi |
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| | |
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| | Here is an example: |
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| | |
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| | .nf |
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| | F00 = 1 |
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| | BAR = 2 |
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| | z = 0 |
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| | |
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| | .ifall [FOO] [BAR] |
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| | x = 1 |
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| | .endif |
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| | |
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| | .ifany [FOO] [foo] [fOo] |
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| | y = 2 |
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| | .endif |
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| | |
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| | .ifnone [BAR] [bar] [Bar] [SOmething] |
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| | z=3 |
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| | .endif |
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| | .fi |
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| | |
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| | When \*(TC finishes processing this, x=1, y=2, and z=0. |
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| | |
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| | You can also use references to environment variables in an existential |
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| | conditional test: |
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| | |
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| | .nf |
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| | .ifany [$MYPROGOPTIONS] |
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| | options = [$MYPROGOPTIONS] |
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| | |
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| | .else |
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| | options = -b20 -c23 -z -r |
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| | |
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| | .endif |
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| | .fi |
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| | |
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| | .SS Comparison Conditional Directives |
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| | |
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| | |
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| | .SS The \'.literal\. Directive |
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| | |
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| |
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| | |
tundra
authored
on 16 Apr 2004