Anaconda (Python) + Cmder (Clink) on Windows - Unify Dueling Custom Prompts - batch-file

Question

If you run Anaconda on windows, you have an activate.bat file which concludes with this line to put your current conda env on the prompt:
set PROMPT=[%CONDA_DEFAULT_ENV%] $P$G
If you run cmder on windows, there is a nice lua script to customize your prompt:
function lambda_prompt_filter()
clink.prompt.value = string.gsub(clink.prompt.value, "{lamb}", "λ")
end
clink.prompt.register_filter(lambda_prompt_filter, 40)
These two scripts do not play very nicely with each other. Clink has an API that seems like I could use to incorporate the change from activate.bat, but I cannot figure out how to call it from a batch file.
My overall goal is to merge these two prompts into the nicer Cmder-style. My thought is to create an environment variable, change activate.bat to check for the existence of the variable, and, if so, call the Clink API to change the prompt instead of set PROMPT. At that point I would think I could create a new filter to cleanly merge the value in. I can't figure out how to call the API from the batch file, though.
Other solutions welcome.
EDIT: Partial, non-working solution
require "os" -- added to top of file, rest in filter function
local sub = os.getenv("CONDA_DEFAULT_ENV")
if sub == nil then
sub = ""
end
print(sub)
clink.prompt.value = string.gsub(clink.prompt.value, "{conda}", sub)
I added a {conda} in the prompt definition at the very beginning; removed the prompt statement from activate.bat, and added this to git_prompt_filter. Prior to using activate, everything is fine - the {conda} gets suppressed by the ''. However, if I use activate and switch into a folder with a git repo to trigger the change, I see:
{conda}C:\...
Does os.getenv not get user set variables? Don't know what else the problem would be. I also tried adding a print, it doesn't print out the contents of CONDA... either.

Answer 1

This is what I do to reset the prompt and add the conda env name to the prompt:
---
-- Find out the basename of a file/directory (last element after \ or /
-- #return {basename}
---
function basename(inputstr)
sep = "\\/"
local last = nil
local t={} ; i=1
for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
--t[i] = str
--i = i + 1
last = str
end
return last
end
---
-- Find out current conda env
-- #return {false|conda env name}
---
function get_conda_env()
env_path = clink.get_env('CONDA_DEFAULT_ENV')
if env_path then
basen = basename(env_path)
return basen
end
return false
end
---
-- after conda activate: reset prompt and add conda env name
---
function conda_prompt_filter()
-- reset to original, e.g. after conda activate destroyed it...
if string.match(clink.prompt.value, "{lamb}") == nil then
-- orig: $E[1;32;40m$P$S{git}{hg}$S$_$E[1;30;40m{lamb}$S$E[0m
-- color codes: "\x1b[1;37;40m"
cwd = clink.get_cwd()
prompt = "\x1b[1;32;40m{cwd} {git}{hg} \n\x1b[1;30;40m{lamb} \x1b[0m"
new_value = string.gsub(prompt, "{cwd}", cwd)
clink.prompt.value = new_value
end
-- add in conda env name
local conda_env = get_conda_env()
if conda_env then
clink.prompt.value = string.gsub(clink.prompt.value, "{lamb}", "["..conda_env.."] {lamb}")
end
end
clink.prompt.register_filter(conda_prompt_filter, 10)

Answer 2

I want to build on #Jan-Schulz answer since it didn't exactly work for me in April 2017.
Instead of editing cmder/vendor/clink/clink.lua I added custom code into cmder/config/prompt.lua which is not overwritten on upgrade (You can add additional modifications to cmder prompt in this file as well using the clink lua api)
I was having an issue where the {lamb} was not being replaced with the proper λ character so I added another filter to run at the end of all processing.
---
-- Find out the basename of a file/directory (last element after \ or /
-- #return {basename}
---
function basename(inputstr)
sep = "\\/"
local last = nil
local t={} ; i=1
for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
--t[i] = str
--i = i + 1
last = str
end
return last
end
---
-- Find out current conda env
-- #return {false|conda env name}
---
function get_conda_env()
env_path = clink.get_env('CONDA_DEFAULT_ENV')
if env_path then
basen = basename(env_path)
return basen
end
return false
end
---
-- after conda activate: reset prompt and add conda env name
---
function conda_prompt_filter()
-- reset to original, e.g. after conda activate destroyed it...
if string.match(clink.prompt.value, "{lamb}") == nil then
-- orig: $E[1;32;40m$P$S{git}{hg}$S$_$E[1;30;40m{lamb}$S$E[0m
-- color codes: "\x1b[1;37;40m"
cwd = clink.get_cwd()
prompt = "\x1b[1;32;40m{cwd} {git}{hg} \n\x1b[1;30;40m{lamb} \x1b[0m"
new_value = string.gsub(prompt, "{cwd}", cwd)
clink.prompt.value = new_value
end
-- add in conda env name
local conda_env = get_conda_env()
if conda_env then
clink.prompt.value = string.gsub(clink.prompt.value, "{lamb}", "["..conda_env.."] {lamb}")
end
end
function fix_lamb()
if string.match(clink.prompt.value, "{lamb}") ~= nil then
clink.prompt.value = string.gsub(clink.prompt.value, "{lamb}", "λ")
end
end
clink.prompt.register_filter(conda_prompt_filter, 1)
clink.prompt.register_filter(fix_lamb, 999)

Answer 3

Why not just delete the line from activate.bat and do all the logic in your cmder profile? CONDA_DEFAULT_ENV will be empty if no environment is active.