30 lines
1020 B
Makefile
30 lines
1020 B
Makefile
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# $NetBSD: varname-dollar.mk,v 1.3 2020/08/19 05:40:06 rillig Exp $
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#
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# Tests for the expression "$$", which looks as if it referred to a variable,
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# but simply expands to a single '$' sign.
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#
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# If there really were a special variable named '$', the expressions ${${DOLLAR}}
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# and $$ would always expand to the same value.
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# Using the dollar sign in variable names is tricky and not recommended.
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# To see that using this variable indeed affects the variable '$', run the
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# test individually with the -dv option.
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DOLLAR= $$
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# At this point, the variable '$' is not defined. Therefore the second line
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# returns an empty string.
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.info dollar is $$.
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.info dollar in braces is ${${DOLLAR}}.
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# Now overwrite the '$' variable to see whether '$$' really expands to that
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# variable, or whether '$$' is handled by the parser.
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${DOLLAR}= dollar
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# At this point, the variable '$' is defined, therefore its value is printed
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# in the second .info directive.
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.info dollar is $$.
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.info dollar in braces is ${${DOLLAR}}.
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all:
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@:;
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