2014-12-16 01:53:52 -0600, Dan Douglas: [...] > That would be one way but I think this can be solved without going quite > so far. How do you feel about these rules? > > 1. If a word that is an argument to declare is parsed as a valid > assignment, then perform the assignment immediately as it appears > lexically. If such a word is parsed as a simple assignment (with or > without an index) then bash treats it as a simple scalar assignment > to > the variable or array element as any ordinary assignment would. If > word > is parsed as an assignment with array initializer list then bash > treats > it as such.
Then, like in my proposal, declare a='(1 2 3)' and declare -a a='(1 2 3}' with valid scalar assignments would work like a='(1 2 3)' so like: a[0]='(1 2 3)' Or are you saying that declare -a/-A should be parsed differently from declare without -a/-A? > 2. Any words that do not parse as valid assignments lexically during > step > 1 undergo the usual set of expansions for simple commands and the > resulting words are saved. > > 3. After evaluation of all words from steps 1-2, those that have > undergone > expansion per 2 are passed as arguments to declare. Declare then > parses > each of these arguments, testing for assignments that became valid as > a result of expansion. During this step, for assignments to variables > that have an array attribute set, or for all assignments if declare > has > been given the -a or -A option, declare will treat assignments that > have > initializer lists as array assignments accordingly. Otherwise, > declare > will treat all assignments as scalar assignments to a variable or > array > element. Words that still fail to parse as valid assignments are an > error. If I understand correctly, does that mean: declare 'a=($(uname >&2))' (assuming "a" was previously declared as an array) should do the same as: eval 'a=($(uname >&2))' ? > I think this covers all the bases and is very close to the current behavior > with one exception. All of the problems Stephane and I have brought up deal > with the situation where a word that parses lexically as a scalar assignment > isn't treated as such, so that is the only required change. I don't think > that change will break many scripts. > > Some observations: > > * This solves the problem without breaking backwards compatibility and allows > declare -p output to continue to function. [...] Well, if "declare -p" continues to function which is not what I understand your proposal to do, then: a='($(uname>&2))' bash -c 's=$(declare -p a); a[0]=foo; eval "$s"' would still run uname. And: a='($(uname>&2))' bash -c 'b[0]=; declare -l "b=$a"' as well. -- Stephane
