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directive-for.mk revision 1.2
      1  1.2  rillig # $NetBSD: directive-for.mk,v 1.2 2020/09/02 22:58:59 rillig Exp $
      2  1.1  rillig #
      3  1.1  rillig # Tests for the .for directive.
      4  1.1  rillig 
      5  1.1  rillig # Using the .for loop, lists of values can be produced.
      6  1.1  rillig # In simple cases, the :@var@${var}@ variable modifier can be used to
      7  1.1  rillig # reach the same effects.
      8  1.1  rillig #
      9  1.1  rillig .undef NUMBERS
     10  1.1  rillig .for num in 1 2 3
     11  1.1  rillig NUMBERS+=	${num}
     12  1.1  rillig .endfor
     13  1.1  rillig .if ${NUMBERS} != "1 2 3"
     14  1.1  rillig .  error
     15  1.1  rillig .endif
     16  1.1  rillig 
     17  1.1  rillig # The .for loop also works for multiple iteration variables.
     18  1.1  rillig .for name value in VARNAME value NAME2 value2
     19  1.1  rillig ${name}=	${value}
     20  1.1  rillig .endfor
     21  1.1  rillig .if ${VARNAME} != "value" || ${NAME2} != "value2"
     22  1.1  rillig .  error
     23  1.1  rillig .endif
     24  1.1  rillig 
     25  1.1  rillig # The .for loop splits the items at whitespace, taking quotes into account,
     26  1.1  rillig # just like the :M or :S variable modifiers.
     27  1.1  rillig #
     28  1.1  rillig # Until 2012-06-03, it had split the items exactly at whitespace, without
     29  1.1  rillig # taking the quotes into account.
     30  1.1  rillig #
     31  1.1  rillig .undef WORDS
     32  1.1  rillig .for var in one t\ w\ o "three three" 'four four' `five six`
     33  1.1  rillig WORDS+=	counted
     34  1.1  rillig .endfor
     35  1.1  rillig .if ${WORDS:[#]} != 6
     36  1.1  rillig .  error
     37  1.1  rillig .endif
     38  1.1  rillig 
     39  1.1  rillig # In the body of the .for loop, the iteration variables can be accessed
     40  1.1  rillig # like normal variables, even though they are not really variables.
     41  1.1  rillig #
     42  1.1  rillig # Instead, the expression ${var} is transformed into ${:U1}, ${:U2} and so
     43  1.1  rillig # on, before the loop body is evaluated.
     44  1.1  rillig #
     45  1.1  rillig # A notable effect of this implementation technique is that the .for
     46  1.1  rillig # iteration variables and the normal global variables live in separate
     47  1.1  rillig # namespaces and do not influence each other.
     48  1.1  rillig #
     49  1.1  rillig var=	value before
     50  1.1  rillig var2=	value before
     51  1.1  rillig .for var var2 in 1 2 3 4
     52  1.1  rillig .endfor
     53  1.1  rillig .if ${var} != "value before"
     54  1.2  rillig .  warning After the .for loop, var must still have its original value.
     55  1.1  rillig .endif
     56  1.1  rillig .if ${var2} != "value before"
     57  1.2  rillig .  warning After the .for loop, var2 must still have its original value.
     58  1.1  rillig .endif
     59  1.1  rillig 
     60  1.1  rillig # Everything from the paragraph above also applies if the loop body is
     61  1.1  rillig # empty, even if there is no actual iteration since the loop items are
     62  1.1  rillig # also empty.
     63  1.1  rillig #
     64  1.1  rillig var=	value before
     65  1.1  rillig var2=	value before
     66  1.1  rillig .for var var2 in ${:U}
     67  1.1  rillig .endfor
     68  1.1  rillig .if ${var} != "value before"
     69  1.2  rillig .  warning After the .for loop, var must still have its original value.
     70  1.1  rillig .endif
     71  1.1  rillig .if ${var2} != "value before"
     72  1.2  rillig .  warning After the .for loop, var2 must still have its original value.
     73  1.1  rillig .endif
     74  1.1  rillig 
     75  1.1  rillig # Until 2008-12-21, the values of the iteration variables were simply
     76  1.1  rillig # inserted as plain text and then parsed as usual, which made it possible
     77  1.1  rillig # to achieve all kinds of strange effects.
     78  1.1  rillig #
     79  1.1  rillig # Before that date, the .for loop expanded to:
     80  1.1  rillig #	EXPANSION+= value
     81  1.1  rillig # Since that date, the .for loop expands to:
     82  1.1  rillig #	EXPANSION${:U+}= value
     83  1.1  rillig #
     84  1.1  rillig EXPANSION=	before
     85  1.1  rillig EXPANSION+ =	before
     86  1.1  rillig .for plus in +
     87  1.1  rillig EXPANSION${plus}=	value
     88  1.1  rillig .endfor
     89  1.1  rillig .if ${EXPANSION} != "before"
     90  1.1  rillig .  error This must be a make from before 2009.
     91  1.1  rillig .endif
     92  1.1  rillig .if ${EXPANSION+} != "value"
     93  1.1  rillig .  error This must be a make from before 2009.
     94  1.1  rillig .endif
     95  1.1  rillig 
     96  1.1  rillig all:
     97  1.1  rillig 	@:;
     98