Retrieve variable name inside function

When working with Julia, it can be useful to retrieve the name of a variable inside a function. This can be particularly helpful when debugging or when you need to dynamically generate code based on the variable name. In this article, we will explore three different ways to achieve this.

Option 1: Using the `@__MODULE__` macro

One way to retrieve the variable name inside a function is by using the `@__MODULE__` macro. This macro returns the name of the current module, which can be used as a proxy for the variable name. Here’s an example:

function get_variable_name(var)
    return string(@__MODULE__)
end

x = 10
println(get_variable_name(x))  # Output: Main

In this example, the `get_variable_name` function takes a variable `var` as input and returns the name of the current module. When we call this function with the variable `x`, it returns “Main”, which is the name of the current module.

Option 2: Using the `@__LINE__` macro

Another way to retrieve the variable name inside a function is by using the `@__LINE__` macro. This macro returns the current line number, which can be used as a proxy for the variable name. Here’s an example:

function get_variable_name(var)
    return string(@__LINE__)
end

x = 10
println(get_variable_name(x))  # Output: 7

In this example, the `get_variable_name` function takes a variable `var` as input and returns the current line number. When we call this function with the variable `x`, it returns “7”, which is the line number where the variable is defined.

Option 3: Using the `@__FILE__` macro

The third way to retrieve the variable name inside a function is by using the `@__FILE__` macro. This macro returns the name of the current file, which can be used as a proxy for the variable name. Here’s an example:

function get_variable_name(var)
    return string(@__FILE__)
end

x = 10
println(get_variable_name(x))  # Output: path/to/current/file.jl

In this example, the `get_variable_name` function takes a variable `var` as input and returns the name of the current file. When we call this function with the variable `x`, it returns the path to the current file where the variable is defined.

After exploring these three options, it is clear that the best option depends on the specific use case. If you need the variable name as a string, Option 1 using the `@__MODULE__` macro is the most suitable. However, if you need a unique identifier for the variable, Option 2 using the `@__LINE__` macro is a better choice. Lastly, if you need the file path where the variable is defined, Option 3 using the `@__FILE__` macro is the way to go.