56

変数のスコープを変数が宣言されている関数に制限する POSIX 準拠の方法はありますか? すなわち:

Testing()
{
    TEST="testing"
}

Testing
echo "Test is: $TEST"

「Test is:」と出力する必要があります。declare、local、および typeset キーワードについて読んだことがありますが、必須の POSIX ビルトインではないようです。

4

7 に答える 7

2

私と一緒に地獄へ旅したいなら、私はそのeval概念をより精巧に実装しました。

これは、準スコープ変数のアカウントを自動的に保持し、より使い慣れた構文で呼び出すことができ、ネストされたスコープを離れるときに変数を適切に設定解除します (単に null にするのではなく)。

使用法

ご覧のとおりpush_scope、スコープに入り、_local準ローカル変数を宣言しpop_scope、スコープを離れます。_unset変数の設定を解除するために使用しpop_scope、そのスコープに戻ったときに再度設定を解除します。

your_func() {
    push_scope
    _local x="baby" y="you" z

    x="can"
    y="have"
    z="whatever"
    _unset z

    push_scope
    _local x="you"
    _local y="like"
    pop_scope

    pop_scope
}

コード

意味不明な変数名の接尾辞はすべて、名前の衝突に対して非常に安全です。

# Simulate entering of a nested variable scope
# To be used in conjunction with push_scope(), pop_scope(), and _local()
push_scope() {
    SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D=$(( $SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D + 1 ))
}

# Store the present value of the specified variable(s), allowing use in a new scope.
# To be used in conjunction with push_scope(), pop_scope(), and _local()
#
# Parameters:
# $@ : string; name of variable to store the value of
scope_var() {
    for varname_FB94CFD263CF11E89500036F7F345232 in "${@}"; do
        eval "active_varnames_FB94CFD263CF11E89500036F7F345232=\"\${SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARNAMES}\""

        # echo "Active varnames: ${active_varnames_FB94CFD263CF11E89500036F7F345232}"

        case " ${active_varnames_FB94CFD263CF11E89500036F7F345232} " in
            *" ${varname_FB94CFD263CF11E89500036F7F345232} "* )
                # This variable was already stored in a previous call
                # in the same scope. Do not store again.
                # echo "Push \${varname_FB94CFD263CF11E89500036F7F345232}, but already stored."
                :
                ;;

            * )
                if eval "[ -n \"\${${varname_FB94CFD263CF11E89500036F7F345232}+x}\" ]"; then
                    # Store the existing value from the previous scope.
                    # Only variables that were set (including set-but-empty) are stored
                    # echo "Pushing value of \$${varname_FB94CFD263CF11E89500036F7F345232}"
                    eval "SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARVALUE_${varname_FB94CFD263CF11E89500036F7F345232}=\"\${${varname_FB94CFD263CF11E89500036F7F345232}}\""
                else
                    # Variable is unset. Do not store the value; an unstored
                    # value will be used to indicate its unset state. The
                    # variable name will still be registered.
                    # echo "Not pushing value of \$${varname_FB94CFD263CF11E89500036F7F345232}; was previously unset."
                    :
                fi

                # Add to list of variables managed in this scope.
                # List of variable names is space-delimited.
                eval "SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARNAMES=\"\${SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARNAMES}${varname_FB94CFD263CF11E89500036F7F345232} \""
                ;;
        esac

        unset active_varnames_FB94CFD263CF11E89500036F7F345232
    done

    unset varname_FB94CFD263CF11E89500036F7F345232
}

# Simulate declaration of a local variable
# To be used in conjunction with push_scope(), pop_scope(), and _local()
#
# This function is a convenience wrapper over scope_var().
#
# Can be called just like the local keyword.
# Example usage: _local foo="foofoofoo" bar="barbarbar" qux qaz=""
_local() {
    for varcouple_44D4987063D111E8A46923403DDBE0C7 in "${@}"; do
        # Example string: foo="barbarbar"
        varname_44D4987063D111E8A46923403DDBE0C7="${varcouple_44D4987063D111E8A46923403DDBE0C7%%=*}"
        varvalue_44D4987063D111E8A46923403DDBE0C7="${varcouple_44D4987063D111E8A46923403DDBE0C7#*=}"
        varvalue_44D4987063D111E8A46923403DDBE0C7="${varvalue_44D4987063D111E8A46923403DDBE0C7#${varcouple_44D4987063D111E8A46923403DDBE0C7}}"

        # Store the value for the previous scope.
        scope_var "${varname_44D4987063D111E8A46923403DDBE0C7}"

        # Set the value for this scope.
        eval "${varname_44D4987063D111E8A46923403DDBE0C7}=\"\${varvalue_44D4987063D111E8A46923403DDBE0C7}\""

        unset varname_44D4987063D111E8A46923403DDBE0C7
        unset varvalue_44D4987063D111E8A46923403DDBE0C7
        unset active_varnames_44D4987063D111E8A46923403DDBE0C7
    done

    unset varcouple_44D4987063D111E8A46923403DDBE0C7
}

# Simulate unsetting a local variable.
#
# This function is a convenience wrapper over scope_var().
# 
# Can be called just like the unset keyword.
# Example usage: _unset foo bar qux
_unset() {
    for varname_6E40DA2E63D211E88CE68BFA58FE2BCA in "${@}"; do
        scope_var "${varname_6E40DA2E63D211E88CE68BFA58FE2BCA}"
        unset "${varname_6E40DA2E63D211E88CE68BFA58FE2BCA}"
    done
}

# Simulate exiting out of a nested variable scope
# To be used in conjunction with push_scope(), pop_scope(), and _local()
pop_scope() {
    eval "varnames_2581E94263D011E88919B3D175643B87=\"\${SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARNAMES}\""

    # Cannot iterate over $varnames by setting $IFS; $IFS does not work
    # properly on zsh. Workaround using string manipulation.
    while [ -n "${varnames_2581E94263D011E88919B3D175643B87}" ]; do
        # Strip enclosing spaces from $varnames.
        while true; do
            varnames_old_2581E94263D011E88919B3D175643B87="${varnames_2581E94263D011E88919B3D175643B87}"
            varnames_2581E94263D011E88919B3D175643B87="${varnames_2581E94263D011E88919B3D175643B87# }"
            varnames_2581E94263D011E88919B3D175643B87="${varnames_2581E94263D011E88919B3D175643B87% }"

            if [ "${varnames_2581E94263D011E88919B3D175643B87}" = "${varnames_2581E94263D011E88919B3D175643B87}" ]; then
                break
            fi
        done

        # Extract the variable name for the current iteration and delete it from the queue.
        varname_2581E94263D011E88919B3D175643B87="${varnames_2581E94263D011E88919B3D175643B87%% *}"
        varnames_2581E94263D011E88919B3D175643B87="${varnames_2581E94263D011E88919B3D175643B87#${varname_2581E94263D011E88919B3D175643B87}}"

        # echo "pop_scope() iteration on \$SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARVALUE_${varname_2581E94263D011E88919B3D175643B87}"
        # echo "varname: ${varname_2581E94263D011E88919B3D175643B87}"

        if eval "[ -n \""\${SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARVALUE_${varname_2581E94263D011E88919B3D175643B87}+x}"\" ]"; then
            # echo "Value found. Restoring value from previous scope."
            # echo eval "${varname_2581E94263D011E88919B3D175643B87}=\"\${SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARVALUE_${varname_2581E94263D011E88919B3D175643B87}}\""
            eval "${varname_2581E94263D011E88919B3D175643B87}=\"\${SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARVALUE_${varname_2581E94263D011E88919B3D175643B87}}\""
            unset "SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARVALUE_${varname_2581E94263D011E88919B3D175643B87}"
        else
            # echo "Unsetting \$${varname_2581E94263D011E88919B3D175643B87}"
            unset "${varname_2581E94263D011E88919B3D175643B87}"
        fi

        # Variable cleanup.
        unset varnames_old_2581E94263D011E88919B3D175643B87
    done

    unset SCOPE${SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D}_VARNAMES
    unset varname_2581E94263D011E88919B3D175643B87
    unset varnames_2581E94263D011E88919B3D175643B87

    SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D=$(( $SCOPENUM_CEDD88E463CF11E8A72A3F9E5F08767D - 1 ))
}
于 2018-05-30T07:23:07.910 に答える
-5

function myfunc {構文を使用して関数をtypeset myvar定義し、変数を定義するために使用します。myfunc(){構文を使用するのではなく、そのように関数を定義すると、すべての一般的な Bourne シェル (bash、zsh、ksh '88 および '93) は、 で定義された変数typeset(および typeset のようなエイリアス) をローカライズしますinteger。

または、車輪を再発明します。どちらがあなたのボートを浮かせます。;)

編集：質問はPOSIXを求めていますが、これはPOSIX準拠の関数定義構文ではありませんが、尋ねた人は後のコメントでbashを使用していることを示しています。真の POSIX メカニズムでは、新しいサブシェルをフォークする追加のオーバーヘッドが必要になるため、別の関数定義構文と組み合わせて「typset」を使用することが最善の解決策です。

于 2013-09-04T03:40:56.043 に答える