varmod-assign.mk revision 1.3
1# $NetBSD: varmod-assign.mk,v 1.3 2020/08/25 18:59:30 rillig Exp $ 2# 3# Tests for the obscure ::= variable modifiers, which perform variable 4# assignments during evaluation, just like the = operator in C. 5 6all: mod-assign 7all: mod-assign-nested 8 9mod-assign: 10 # The ::?= modifier applies the ?= assignment operator 3 times. 11 # The ?= operator only has an effect for the first time, therefore 12 # the variable FIRST ends up with the value 1. 13 @echo $@: ${1 2 3:L:@i@${FIRST::?=$i}@} first=${FIRST}. 14 15 # The ::= modifier applies the = assignment operator 3 times. 16 # The = operator overwrites the previous value, therefore the 17 # variable LAST ends up with the value 3. 18 @echo $@: ${1 2 3:L:@i@${LAST::=$i}@} last=${LAST}. 19 20 # The ::+= modifier applies the += assignment operator 3 times. 21 # The += operator appends 3 times to the variable, therefore 22 # the variable APPENDED ends up with the value "1 2 3". 23 @echo $@: ${1 2 3:L:@i@${APPENDED::+=$i}@} appended=${APPENDED}. 24 25 # The ::!= modifier applies the != assignment operator 3 times. 26 # The side effects of the shell commands are visible in the output. 27 # Just as with the ::= modifier, the last value is stored in the 28 # RAN variable. 29 @echo $@: ${echo.1 echo.2 echo.3:L:@i@${RAN::!=${i:C,.*,&; & 1>\&2,:S,., ,g}}@} ran:${RAN}. 30 31 # The assignments happen in the global scope and thus are 32 # preserved even after the shell command has been run. 33 @echo $@: global: ${FIRST:Q}, ${LAST:Q}, ${APPENDED:Q}, ${RAN:Q}. 34 35mod-assign-nested: 36 # The condition "1" is true, therefore THEN1 gets assigned a value, 37 # and IT1 as well. Nothing surprising here. 38 @echo $@: ${1:?${THEN1::=then1${IT1::=t1}}:${ELSE1::=else1${IE1::=e1}}}${THEN1}${ELSE1}${IT1}${IE1} 39 40 # The condition "0" is false, therefore ELSE1 gets assigned a value, 41 # and IE1 as well. Nothing surprising here as well. 42 @echo $@: ${0:?${THEN2::=then2${IT2::=t2}}:${ELSE2::=else2${IE2::=e2}}}${THEN2}${ELSE2}${IT2}${IE2} 43 44 # The same effects happen when the variables are defined elsewhere. 45 @echo $@: ${SINK3:Q} 46 @echo $@: ${SINK4:Q} 47SINK3:= ${1:?${THEN3::=then3${IT3::=t3}}:${ELSE3::=else3${IE3::=e3}}}${THEN3}${ELSE3}${IT3}${IE3} 48SINK4:= ${0:?${THEN4::=then4${IT4::=t4}}:${ELSE4::=else4${IE4::=e4}}}${THEN4}${ELSE4}${IT4}${IE4} 49