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declare -x non-exportable variable types

From: Léa Gris
Subject: declare -x non-exportable variable types
Date: Tue, 22 Feb 2022 19:35:20 +0100
User-agent: Telnet/1.0 [tlh] (PDP11/DEC)

declare -x variable with unexportable flag/type is handled quite inconsistently:

$ unset int_value && declare -ix int_value=42 && bash -c 'declare -p int_value'
declare -x int_value="42"

$ unset array && declare -ax array=(foo bar) && bash -c 'declare -p array'
bash: line 1: declare: array: not found

$ unset assoc && declare -Ax assoc=([key1]=foo [key2]=bar) && bash -c 'declare -p assoc'
bash: line 1: declare: assoc: not found

$ unset upper && declare -ux upper='hello' && bash -c 'declare -p upper'
declare -x upper="HELLO"

$ unset lower && declare -lx lower='WORLD' && bash -c 'declare -p lower'
declare -x lower="world"

$ unset str && unset -n ref && declare str=hello && declare -nx ref=str && bash -c 'declare -p ref'
declare -x ref="str"

The inconsistency is that sometimes:
- It exports the variable with its translated value (integer to string, upper, lower) - It exports nothing of array or associative array, despite that in Bash, array referenced without an index returns the first element, but not when exported. - It export the reference name of nameref, despite it could export the value of the referee.

My stance on this is that there is no real consistent way to export variables with incompatible flags; and I wonder if to be consistent, the declaration statement could be erroring instead, when the other variable flag are incompatible with export.

For the built-in export or system export command, a consistent conversion of the value sounds an acceptable behavior:

export int_value # export with string of value
export array # export with value of first elmeent
export assoc # export empty value (same as referencing an associative array without a [key].
export upper; export lower # export with converted value
export nameref # export with value of the referee

This means that the export command would expand the variable value before exporting, but the declare, local and typeset statements would error if flags are incompatible with -x export.

Léa Gris

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