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#### var ref to array 'preHooks[@]' |
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# |
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# This idiom discussed on |
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# https://github.com/NixOS/nixpkgs/pull/147629 |
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|
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shopt -s eval_unsafe_arith 2>/dev/null # required for OSH |
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|
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show() { |
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echo show |
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|
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# These are actually different |
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argv.py ${!hooksSlice} |
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|
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argv.py ${!hooksSlice+"${!hooksSlice}"} |
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} |
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|
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hooksSlice='preHooks[@]' |
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|
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preHooks=() |
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show |
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|
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preHooks=('foo bar' baz) |
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show |
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|
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# WTF this exposes a difference? But not the test case below? |
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|
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# What's happening here? |
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# Uncomment this and get an error in bash about hookSlice, even though we never |
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# undefined it. |
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|
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#wtf=1 |
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# |
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# line 6: !hooksSlice: unbound variable |
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|
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if test -n "$wtf"; then |
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# 4.4.0(1)-release |
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# echo $BASH_VERSION |
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|
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set -u |
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preHooks=() |
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show |
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|
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preHooks=('foo bar' baz) |
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show |
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fi |
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|
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## STDOUT: |
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show |
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[] |
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[] |
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show |
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['foo', 'bar', 'baz'] |
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['foo bar', 'baz'] |
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## END |
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|
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#### Same as above with set -u |
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show() { |
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echo show |
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|
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# These are actually different |
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argv.py ${!hooksSlice} |
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|
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argv.py ${!hooksSlice+"${!hooksSlice}"} |
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} |
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|
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hooksSlice='preHooks[@]' |
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|
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set -u |
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preHooks=() |
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show |
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|
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preHooks=('foo bar' baz) |
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show |
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|
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## STDOUT: |
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show |
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## END |
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## status: 1 |
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|
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|
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#### ${!ref} to undefined array |
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|
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set -u |
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shopt -s eval_unsafe_arith || true 2>/dev/null |
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|
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#preHooks=() |
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hookSlice="preHooks[@]" |
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|
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argv.py ${!hookSlice+"${!hookSlice}"} |
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|
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for element in ${!hookSlice+"${!hookSlice}"}; do |
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echo $element |
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done |
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|
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## STDOUT: |
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[] |
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## END |
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|
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#### ${!ref} to undefined string var is fatal, INCONSISTENT with array |
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hookSlice='preHooks' |
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|
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argv.py ${!hookSlice} |
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|
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set -u |
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|
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argv.py ${!hookSlice} |
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|
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echo end |
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|
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## status: 1 |
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## STDOUT: |
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[] |
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## END |
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|
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#### export with dynamic var name += |
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|
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orig() { |
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export NIX_LDFLAGS${role_post}+=" -L$1/lib64" |
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} |
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|
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new() { |
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local var_name="NIX_LDFLAGS$role_post" |
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local value=" -L$1/lib64" |
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|
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eval "$var_name"+='$value' |
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export "$var_name" |
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} |
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|
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role_post='_foo' |
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|
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# set -u |
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|
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if test -n "${BASH_VERSION:-}"; then |
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orig one |
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fi |
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|
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declare -p NIX_LDFLAGS_foo # inspect it |
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unset NIX_LDFLAGS_foo |
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|
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new one |
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|
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declare -p NIX_LDFLAGS_foo # inspect it |
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|
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## STDOUT: |
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declare -x NIX_LDFLAGS_foo=" -Lone/lib64" |
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declare -x NIX_LDFLAGS_foo=" -Lone/lib64" |
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## END |
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## OK osh STDOUT: |
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declare -x NIX_LDFLAGS_foo=' -Lone/lib64' |
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## END |
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|