是否有更一致的方式来声明Bash变量和函数？

2019年8月4日 117次阅读

我一直在决定如何在
Bash中声明变量或函数.

鉴于以下假设：

> Bash是唯一可用的脚本语言.
>命名约定无关紧要.

在全局变量的情况下,我应该使用：

> foo = bar – 函数内部和外部？
> declare -g foo = bar – 函数内部和外部？
> local -g foo = bar – 函数内部？

在局部变量的情况下,我应该使用：

>本地foo =吧
>声明foo = bar

在只读变量的情况下,我应该使用：

> declare -r foo = bar
> local -r foo = bar
> readonly foo – 在下一行没有-r标志的[1.]或[2.]之后.

在函数的情况下,我应该使用：

> foo(){echo bar; }
> foo {echo bar; }
> function foo(){echo bar; }
> function foo {echo bar; }

最佳答案 为了忘记它,我在.bashrc顶部附近以及每个Bash shell脚本文件中定义了以下内容：

# Allow to define an alias.
#
shopt -s expand_aliases

# Defines a function given a name, empty parentheses and a block of commands enclosed in braces.
#
# @param name the name of the function.
# @param parentheses the empty parentheses. (optional)
# @param commands the block of commands enclosed in braces.
# @return 0 on success, n != 0 on failure.
#
alias def=function

# Defines a value, i.e. read-only variable, given options, a name and an assignment of the form =value.
#
# Viable options:
#   * -i - defines an integer value.
#   * -a - defines an array value with integers as keys.
#   * -A - defines an array value with strings as keys.
#
# @param options the options. (optional)
# @param name the name of the value.
# @param assignment the equals sign followed by the value.
# @return 0 on success, n != 0 on failure.
#
alias val="declare -r"

# Defines a variable given options, a name and an assignment of the form =value.
#
# Viable options:
#   * -i - defines an integer variable.
#   * -a - defines an array variable with integers as keys.
#   * -A - defines an array variable with strings as keys.
#
# @param options the options. (optional)
# @param name the name of the variable.
# @param assignment the equals sign followed by the value. (optional)
# @return 0 on success, n != 0 on failure.
#
alias var=declare

# Declares a function as final, i.e. read-only, given a name.
#
# @param name the name of the function.
# @return 0 on success, n != 0 on failure.
#
alias final="readonly -f"

以上定义允许我举例说：

> def foo {echo bar; }.
>最终的foo
> var foo = bar
> val foo = bar

如注释所示,您可以混合和匹配各种变量标志,例如var -g foo = bar表示全局(-g)变量(var)或val -Ai foobar =([foo] = 0 [bar] = 1)对于只读(val),关联数组(-A)由整数(-i)值组成.

这种方法也带有隐式变量范围.此外,任何使用JavaScript,Java,Scala等语言编程的软件工程师都应熟悉新引入的关键字def,val,var和final.

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