How to open a file with variable in the path?

Question

gf runs fine with absolute or relative path.
Is it possible to open a file with variable in the path?

For example, in a tcl file:

...
set FILE_ROOT /user/abc
...   
read_file ${FILE_ROOT}/some/path/abc.txt

How to open ${FILE_ROOT}/some/path/abc.txt inside vim?

Answer 1

Overview

• Vim user Fisher wishes to use gf to open a file path with an embedded variable

Quick Answer (TL;DR)

• Use :execute and :expand together to run a command with embedded variables
• (eg) :let @m='/my/file/path/uu137fisher1666889936.txt' | :execute(':edit '. expand(@m))

Detailed Answer

Context

• Vim version 7.4
• file editing command gf

Problem

• Use-case scenario: Developer wishes to use gf to edit a text file in vim

Solution

• Use :execute and :expand together to run a command with embedded variables
• (optional) create a vim function that runs the relevant commands and attach a keybinding for a custom-made gf variant

Example

populate a variable or register with the desired path

• :let @m='/my/file/path/uu137fisher1666889936.txt'

access that variable or register with execute() and expand()

• :execute(':edit '. expand(@m))

create a special keybinding with custom gf variant

• :noremap <leader>gf :call My_special_gf_variant()<CR>

Pitfalls

• the gf command is generally designed to work with literal paths, with some support for wildcard characters
• the exact use-case of interpolating or expanding variables is not depicted in :help gf for the Vim version referenced in this answer
• the example in this answer demonstrates how to read from a vim register instead of a vim variable, but the same basic principle applies to both contexts
• the answer will change depending on what context is responsible for resolving the relevant variable in use
• for example:
  • is it a MSFT Windows environment variable?
  • is it a BASH shell variable?
  • is it a variable declared in init.vim or some other vimscript file?
  • if declared in vimscript, has the relevant vimscript been included? (eg) :source foobar.vim

See also

• websearch://uu137fisher1666889936
• Vim :help expand
• Vim :help gf
• Vim :help netrw-gx